In the mid-90s, Seismic produced a 66mm cruising wheel for assembly with Seismic trucks on “Richter 7.1” completes, featuring slalom decks hand-built on special commission by the legendary Bob Turner. Like the rollout of the original Seismic spring truck in 1994, this plan was years ahead of its time!

Seismic began pouring high-performance wheels on a larger scale in 2004, when we took over the 3dm line. The original Cambria, Avalon and Avila shapes utterly dominated international slalom racing for years. They’re still used by elite racers, cruisers and carvers around the world. Since 2005 we’ve developed even more advanced wheels under our flagship Seismic brand, including shapes that have won numerous World Championship titles in both Slalom and Downhill racing.



Small bubbles on the angled inside wheel faces are not uncommon – especially in softer urethane formulas and in race-style wheels with steeply-sloped inside faces.  These are actually a sign that the wheels were truly gravity-poured at a relatively low temperature (“cold-poured”), instead of injection-molded under high heat and pressure (which speeds production but compromises urethane performance).

Because of this “cold” pouring, air trapped in the urethane brew rises to the top of the mold cup (the inside faces) more slowly, and sometimes creates small bubbles as the material sets.

Bubbles like these have no effect whatsoever on wheel performance or durability.  In fact, a great many elite international professional races (including World Championships) have been won on Seismic wheels with small bubbles on the inside faces.

Exception: If one or more of your wheels has large bubbles right on the lip, or at the interface between the urethane and the hub, please contact us with photos for evaluation.

More rarely, extremely small, froth-like bubbles can form on the running surfaces, and these may become visible during the early “break-in” period as the tiny bubbles fill in with dirt and grime from the road. Continued light riding quickly wears through these minuscule bubbles, and they pose no performance concern whatsoever.

Gouges and Tears

Seismic and 3dm wheels are poured at the world’s leading wheel factory, using the world’s finest urethane. We’ve conducted extensive lab tests that subject wheels to extreme stresses as they roll on a smooth drum simulating a uniform road. Our wheels never tear or chunk under these lab conditions.

But chunks and tears are an ever-present risk as flexible urethane wheels roll, turn, slide, and impact on imperfect surfaces in the real world.

Even the best auto and bike tires can go flat if they roll over nails or glass. Likewise, even the best skateboard wheels can tear on nails, glass, gravel, pebbles, and small sharp residue on roads that otherwise seem smooth. In both cases, the damage is almost always a matter of physics and bad luck, not product defect. Probably only wheels made of steel would be 100% resistant to tears and chunks!

Seismic follows the basic protocol of the auto and bike industries. We evaluate each report on its own merit, and we sometimes replace torn wheels on a courtesy basis. But we usually don’t warranty wheels damaged by sharp surface elements without very clear evidence of product defect.

The most common causes of tearing and chunking include:

  • sliding and hard cornering at higher speeds on rough surfaces
  • drifting onto road shoulders and rolling / sliding over gravel, rocks, glass, and dirt
  • rolling over sharp sidewalk edges – especially when most of the wheel loses contact and the inside lip bears all the load as it rolls over the sharp edge
  • kick-turning on rough surfaces, which can shred the edges of longboard wheels in a single afternoon
  • hard impacts on rough or irregular surfaces, during the landing phase of an aerial or board flip

A tear that runs along a significant portion of a wheel’s circumference (see photos above) is clear evidence that damage occurred as the wheel rolled or slid over a sharp surface element.

Harder wheels, and wheels with rounded edges, don’t catch as easily on jagged surface features. Softer wheels, and wheels with sharper edges, are more vulnerable to damage – especially under heavier, faster, and/or more aggressive riders.

Soft urethane can even totally absorb bits of glass, jagged pebbles, and beer-can tabs. These objects can then work their way deep into a wheel and later split it open from the inside. (Think of the “Aliens” films!)

High-rebound race formulas – like Seismic Defcon™ – are somewhat more vulnerable to tearing. Their faster rate of energy return is only possible because they have an inherently “looser” molecular structure. But experienced racers generally agree that the added speed is worth it. Before doing any slides, we recommend breaking in all Defcon race wheels by riding them for 5 or 10 minutes – until the glossy outermost “skin” is gone.

Very tall, narrow race wheels (like the Seismic 85mm Speed Vent) may be more vulnerable to tearing and chunking, for at least two reasons: 1) The longer “lever arm” between the axle and lips amplifies forces acting on the edges; and 2) Those forces are not distributed across a wide contact patch.

On very rare occasions, an air bubble trapped in a wheel lip can break open under normal riding stresses on good surfaces. Remnants of burst bubbles are fairly easy to see, and we replace such wheels. But the riding surface is definitely the culprit if more than one wheel in a set of four has torn or chunked. (It is incredibly unlikely that one set would include multiple wheels with large air bubbles on the lip.)

Wheel Rub

Before skating any new setup for the first time, you should always test on carpet for the possibility of wheel rub. Wheel rub is a “systems issue,” related to the total deck-wheel-truck combination. The manufacturers of individual components can’t guarantee that you won’t get wheel rub when combining their product with parts from other companies.

The axle height and tilt range of Seismic trucks were carefully engineered for maximum performance options. If you’re experiencing wheel rub, your best solution is to use more riser under your trucks, and/or smaller wheels, and/or a deck with wheel wells or wheel cutouts.

If your bodyweight is on the high side, another issue to consider is torsional deck flexion. Under the weight of heavy skaters, decks twist more than normal. This means that the deck actually flexes toward the wheels during turns (especially at the nose), making wheel bite more likely. Extra-large skaters should consider choosing stiffer, thicker decks, possibly with concave, to gain more torsional stiffness.

Wheel Wobbles

Wobbly wheels (wheels with misaligned cores) show up now and then, no matter what brand you’re talking about. It’s just a fact of life, even with the most modern technologies used to mold skateboard wheels. Of course, we do our absolute best to minimize the number of wheels that are wobbly. Wheels with significant wobbles – with cores so out of alignment that performance is effected – are rare. Unfortunately, we cannot entirely eliminate wobblers and still offer wheels at prices that most skateboarders can afford.

If one out of four of your wheels seems to have a significant wobble, you got very unlucky. Please contact us about the wobble (or other defect) before riding the wheels, and we’ll work with you to figure out what’s up. If the problem is real, we’ll take care of it. Just note that if you have a genuinely bad wheel, we will replace the problem wheel but not the whole set of wheels. We make no exceptions to this policy. Also, if you’ve logged a lot of miles on the wheel, it’s too late. A well-worn wheel is one that you got your money’s worth from!

The odds are incredibly low that two or more of your wheels have a significant wobble. If you think you have more than one wobbly wheel, you may be expecting too much. Aerospace tolerances are impossible to deliver at affordable prices. Miniscule wobbles – the type that you have to strain to see, the type that you can’t notice in any way when you’re riding – are common and do not effect performance. In fact, they normally disappear or diminish as wheels break in.

If you’re unsure about one or more of your wheels, first check to make sure you have bearing spacers of the correct size (0.400-inch) installed between the bearings. Bearing spacers help keep the bearings aligned in the wheel core; neglecting to use them can make good wheels appear wobbly. Also note that appearances can be deceiving. Even with good bearings and bearing spacers, some wheels with perfect core alignment may look wobbly when spun by hand. How is this possible? When wheels are popped out of the molds, the urethane sometimes settles unevenly as it cools, leaving small excesses around the edges. Also, sometimes the “flash” (excess urethane) on the inside lip is trimmed off unevenly after molding, creating an edge that appears to wiggle as the wheel spins.

These two factors – uneven cooling and asymmetrical trim – can make good wheels appear wobbly when free–spun. To distinguish these from true wobblers (wheels with misaligned cores), look at the inside and outside edges separately during a spin test. In a true wobbler, the inside and outside edges will oscillate with a perfectly even rhythm, and the middle of the wheel will probably not stay level.

Wheels with high spots, or wheels with an uneven trim, will usually show only one edge wobbling during a spin test. If a wheel has multiple high spots, both edges may look wobbly, but the middle usually stays level and the oscillation will not have an even rhythm. Again, such wheels are generally perfectly fine to use.

Damaged Hubs

Seismic wheel hubs are made of the strongest composite material available in the industry. But under extreme stresses, even the best skateboard wheel hubs can deform or even melt. Three factors are almost always at play: damaged or seized bearings; the absence of spacers supporting the bearings in their pockets; and loose wheel nuts.

Bearings that are damaged or seized may appear to spin OK at rest, but in a mater of seconds they can reach over 400° F, hot enough to melt or deform virtually all molded plastics.

For optimal performance, use Seismic Tekton bearings, or else normal bearings with proper spacers between them. Otherwise aggressive high-speed carves and hard slides over-stress the hub bearing supports and the bearings themselves. The bearings can easily suffer damage, making them more likely to seize and create enough heat to melt any hub on the market. Axles with poor diameter tolerances only make these matters worse.

In addition, if your wheel nuts are not tightened snug against the bearings, your wheels lurch on the axles every time you carve or slide. This means the bearings slam back-and-forth against the hanger and the nut. Over time, the repeated impacts over-stress the hub bearing supports, especially if you’re not using Tekton bearings or normal bearings with good spacers. The bearings themselves will also suffer damage – leading to noise, diminished performance, and a greater likelihood of seizure.

Unfortunately, if you ride without bearing spacers and/or with loose wheel nuts, Seismic cannot warranty wheels with damaged hubs.

For optimal performance, keep your wheel nuts snug and use Seismic Tekton bearings. Their integrated flanged spacer elements assure optimal alignment and support during even the most aggro riding.


Breakthrough self-aligning design corrects for flaws in bearing seat levelness, bearing seat spacing, axle diameter and axle straightness.

More than two years in development, Seismic Tekton™ bearings feature wide, flat contact surfaces at the ends of integrated, custom-machined half-spacers. The broad flanges square up, co-align and self-stabilize inside your wheels – correcting for flaws in bearing seat levelness, bearing seat spacing, axle diameter and axle straightness.
The Tektons literally block themselves from sitting or rocking out of alignment, so they stay straighter than any other bearing system ever. Your wheels roll faster with better control, while the bearings last longer and stay quieter.
 Other features include: steel balls, nylon retainers, black outer casing, removable rubber-coated steel seals with printed graphic, and a proprietary lubricant combining both oil and grease.
The inner race is stepped underneath the seal to resist contamination, and it’s stepped between the bearing and the flange to save weight. On the side opposite the flange, the inner race extends 0.5mm to form a thin integrated washer. No bearing spacers, axle washers, or World Record budgets required!


Advanced Self-Alignment

Patented design integrates wide, flat contact surfaces on ends of custom-machined half-spacers. Broad flanges square up, co-align, and self-stabilize inside wheels. Corrects for flaws in bearing seat levelness and spacing / axle diameter and straightness.

Self-straightening: Prevents bearings from sitting or rocking out of alignment better than any other system.

Self-supporting: Protects bearings from internal stresses.

Advanced Construction

Packed with premium “high RPM” light grease, formulated by one of the world’s most renowned lubricant suppliers.

Inner race specially contoured underneath seal to resist contamination, and stepped between bearing and flange to save weight. Extends 0.5mm on side opposite flange to form thin integrated washer.

Retainers made of Dupont engineering-grade Nylon for superior durability.

Degree of play engineered for balanced performance and wear across all skating disciplines. Not too much, not too little.

Advanced Ball Specifications

Balls rated P4, the highest grade available. Superior concentricity, surface smoothness, speed and durability.

6-Ball Tektons constructed with fewer, larger, stronger balls. Less total ball-raceway surface contact, less friction, quicker acceleration.

Ceramic Tektons feature lightweight, rustproof trisilicon tetranitride (Si3N4) balls. Lighter, tougher balls mean less friction, quicker acceleration, more speed! Harder than steel, black ceramic crushes debris, keeps raceways clean. Runs cooler, too.



When pressing your bearings into the wheels, use a proper skate tool, and be firm but not rough. Otherwise you can easily damage the seals and cages.

Tighten all wheel nuts snug against the Tektons. Otherwise your wheels will lurch on the axles every time you carve or slide. This can easily damage the bearings as they slam back-and-forth against the hanger and the nut.

If you have trouble getting your bearings on or off the axles, the axle diameter is probably too thick or irregular. This is more common with so-called “precision” trucks, whose axles may be ground with diameters too close to 8.0mm or 10.0mm. Usually all it takes to correct minor fit issues is some light sanding on the axle and/or the bearing bore.

The inner race of standard skateboard bearings has an inner diameter of 8.0mm, with a small manufacturing tolerance. For greatest wheel and bearing precision, axles should have a diameter of around 7.95mm – 7.97mm. Avoid trucks with axles that claim to be exactly 8.0mm in diameter. Bearings may not fit on them, or they may get stuck after installation. Similarly, for 10mm bearings, axles should have a diameter slightly under 10.0mm. Otherwise the bearings are likely to have fit issues.

NOTE: The broad Tekton flanges may not fit hub-less streetboard wheels with old-style, oversized bearing supports, which sometimes leave the wheel’s central hole smaller than the flange (15mm in diameter). Use Tekton LITE bearings for wheels of this type.

Cleaning and Lubrication

Seismic Tekton bearings are manufactured to exacting standards and come pre-lubricated with a proprietary blend of oil and grease. A lot of myths have begun circulating about how often bearings need to be cleaned and re-lubricated. There is no need to clean or add any additional lubricant to new Tekton bearings.

We recommend wiping excess grime off the outer seals every week or two. Clean and re-lube the bearings only as necessary, depending on how much you ride and the conditions that you ride in. Clean and re-lube more frequently if you ride through water, mud or sand. Avoid excessive cleaning, as this increases the risk of accidental damage to the seals and cages.

Please note, too, that the inside face of the Tektons is unsealed. This means you can clean and re-lube without removing the rubber-coated steel seals on the outside. Just soak the bearings, rinse, and let dry. We recommend cleaning with isopropyl alcohol (70% solution or greater), denatured alcohol, Gumout® carburetor cleaner, or acetone.

A variety of good lubricants are readily available, such as Bones Speed Cream. Avoid lubricant products that include citrus-based cleaning agents, since their acidic content can lead to corrosion.

If you choose to remove the seals, be extremely careful when removing and replacing them. Do not use large hand tools or excess force, as this can damage the seals and even the ball retainers. Bent seals may not properly re-seat and can pop off during use. The bent sections can also have friction with the balls and lead to diminished speed. Damaged or cracked ball retainers compromise bearing performance even more seriously. Note that Seismic cannot warranty bearings that are damaged during disassembly or reassembly.

Finally, please do not remove the ball cages from the outer casings – there is no need to take this step to clean your bearings. The plastic cages are quite vulnerable to snapping when popped out and back in. And outside of a professional bearing factory, it is nearly impossible to precisely reassemble bearings that have been completely disassembled in this manner.

Bearing Noise

Deep-groove bearing designs inevitably make a small amount of noise. This may be more noticeable in the Tektons due to their single-seal design. This slight noise is irrelevant to performance and is actually a sign of a well-spaced assembly.

In addition, bearings lubricated with oil or a lighter oil-grease mixture, such as the Tektons, are often noisier than bearings lubricated with very thick grease. In our opinion, this is a small price to pay for the added speed that a lighter lubricant brings.

Axles with poor tolerances (imprecise diameter, uneven surface) are a very common cause of truly excessive bearing noise. Excess play between the bearings’ inner races and the axles allows for micro-rattling and creates a miniature “echo chamber.”

Dust, dirt, and grime can obviously muck up the bearings’ inner works and cause noise, too. Clean and re-lube your bearings as necessary. Just be very careful not to bend the seals or damage the cages when you disassemble and reassemble your bearings, or when you install and remove them from the wheels. This is another common cause of noisy, diminished performance.

The Fallacy of Free-Spin Testing

Free-spinning bearings or wheels by hand, under zero load, is not a true or meaningful test of bearing performance. Advanced lubricants, such as those used in Tekton bearings, are designed to perform best when “warmed up” by real-world stresses.

Bearings that are under-lubricated, or lubricated with very thin oil, may have a long free-spin.  The same may be true of bearings with sloppy assembly tolerances.  But during actual riding they won’t perform as well or hold up as long.

Bearings with good assembly tolerances and high-quality lubricant are usually FASTER during actual skating, even though they may have a shorter free-spin.  In fact, most world speed records have been set on bearings with modest free-spin.

All that really matters is how bearings handle under the load of bodyweight – rolling, turning, and sliding on real roads.

A number of external factors, outside the control of the bearing manufacturer, can also shorten free-spin time (and create added noise).  These include:
• over-tightened or under-tightened axle nuts
• poor axle tolerances
• crooked / incorrectly-spaced bearing seats in the wheels
• bearings that are not fully or correctly seated within the wheels
• contamination with dust, dirt, or grime

For all of the above reasons, we do not normally warranty Tekton bearings that free-spin less than a rider expects.  Free-spin time truly has no significance (unless of course the bearing is absolutely locked or frozen).

Bearing Play: Fact and Fiction

Bearing play stems primarily from two sources in combination: 1) a necessary tolerance between the axle’s outer diameter and the bearing’s inner diameter (axle tolerance); and 2) a necessary tolerance between the bearing balls and the groove or raceway (raceway tolerance).

Many myths are circulating in the longboard world about bearing play. A properly functioning bearing requires some play of both kinds. It is a mistake to assume that “the less play the better.” Also, during actual rolling motion, the momentum of the balls tends to minimize axial play compared to what is observable when the bearings are at rest.


A small amount of play between the axle’s outer diameter and the bearing’s inner diameter is normal and necessary. Otherwise it would be impossible to slide bearings onto axles by hand. This is usually the main source of play once wheels are assembled and snugly fastened to a truck

Seismic Tekton bearings are designed to correct for most sources of misalignment. However, all 8mm bearings have play on standard 5/16-inch (7.9375mm) axles. This is simple mechanics, not an issue of bearing design or quality. Even higher-precision axles have minute high and low spots that add to play, depending on how the bearings’ inner races are “clocked” on the axle when the wheel nuts are tightened down.

For greatest wheel and bearing precision, use trucks that have axles around 7.95mm – 7.97mm in diameter. Avoid trucks with axles that claim to be exactly 8.0mm in diameter – bearings are likely to get stuck on them.


Inside an individual bearing, a small amount of play between the inner race and the outer casing is the result of a necessary tolerance between the balls and the raceway. Minimizing the gap between the balls and the groove decreases internal play, but it also increases friction, reduces speed, and shortens bearing life.

Loose bearings (with a lot of internal play) are more durable, but they result in wheels that roll less precisely, which compromises grip and sliding characteristics. Tight bearings (with very little internal play) are slower and prone to damage. Optimal bearing performance is a matter of engineering the appropriate amount of internal play. Not too much and not too little.

Note that packing a bearing with thick grease can create the illusion of a “tight” bearing. However, lubricating with grease that is too thick (or too cheap) can make for a slower bearing. In addition, thick grease heats up and grows thinner when the bearings spin at high speeds for a sustained period of time. Then the inner race and outer casing may exhibit more play than when the bearings are “cold.”

Furthermore, over time bearing lubricant evaporates and spins out, particularly if very light oil is used or if one side of the bearing is unsealed. As this happens, the gap between the balls and the grooves grows larger, since less lubricant is present. In turn, the amount of internal play increases, possibly to the point of compromising wheel performance. Clean and re-lube your bearings as necessary.

It goes without saying that bearings damaged during cleaning (bent seals or cages) may exhibit excess play, as well as noisy, diminished performance. Also, like any other product, bearings naturally wear and degrade over time, particularly if ridden intensively.


Other factors that contribute to bearing play include variations in the ID of the bearing seats. During production, they may shrink more on one side of the wheel hub than the other.

Even a properly assembled and mounted wheel with high-quality bearings has at least 0.15-degrees of play on a standard axle. But for most bearings under load, 1 degree of torsional deviation between the inner race and outer casing will cause damage resulting in loss of speed and increased noise. Beyond poor axle tolerances, a number of other factors can easily contribute to this type of damage: loose axle nuts; absence of spacer support between the two bearings in a given wheel; and crooked or flexible bearing pockets in the wheel hubs.

The effect of loose axle nuts should not be underestimated. Wheels that are not snugly fastened are free to lurch onto the threaded portions of the axles, which have a substantially smaller diameter. In turn, this creates a significantly higher potential for excess play leading to permanent bearing damage and slow, noisy bearing performance.

10mm Tekton Bearings

Many so-called 10mm axles have an Outer Diameter in the range of 9.85mm – 9.957mm. The 10mm Tektons have an Inner Diameter spec in the range of 9.97mm – 9.99mm, for greatest precision with the best 10mm axles. They have more play on lower-grade 10mm axles.


In 1993, Seismic patented one of the most original and sophisticated technologies ever developed for skateboarding. The first of the new generation of longboard trucks, it was so far ahead of its time that even we had to poke fun at it in our September 1994 TransWorld Skateboarding ad! But soon enough, our spring-loaded design inspired cheap imitations in off-road skateboards and surfing cross-trainers.
Redesigned in 2003 and again in 2015, the Seismic spring truck technology now offers impressive tuning options for the discerning skater, and advanced performance for longboarding, racing, all-purpose cruising, Old School park/pool styling, and snow/surf cross-training.


Seismic springs come in seven (7) different color-coded strengths. The standard pre-installed springs are designed to optimally blend turning ease, stability and resilience for the average user. Of course, what works best for you will vary depending on size, style, personal preferences, and the disciplines you practice.

The Seismic metal coil springs’ rapid energy return capitalizes on your thrust-carving action more efficiently than traditional urethane bushings (which are basically primitive damping springs). The quicker the board rights itself after you unweight, the stronger you can pump. For more stability, increase spring tension, buy heavier springs, or switch to the stable-turning baseplate. For more maneuverability, decrease spring tension, try lighter springs, or switch to the quick-turning baseplate.

For super-specific recommendations, view our bodyweight chart

75 lbs / 34 kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Super-Light or Extra-Light
Rear 30° Super-Light or Extra-Light
Park / Pool Front 45° Max-Light
Rear 30° Super-Light
Ramp Front 30° or 45° Super-Light
Rear 30° Extra-Light
Longboard Front 45° Max-Light
Rear 30° (performance)
45° (recreation)
Slalom Front 45° Max-Light
Rear 30° (performance)
45° (recreation)
Downhill Front 30° Light
Rear 30° Light


100 lbs / 45 kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Extra-Light or Light
Rear 30° Extra-Light or Light
Park / Pool Front 45° Super-Light
Rear 30° Extra-Light
Ramp Front 30° or 45° Extra-Light
Rear 30° Light
Longboard Front 45° Max-Light or Super-Light
Rear 30° (performance)
45° (recreation)
Super-Light or Extra-Light
Slalom Front 45° Max-Light or Super-Light
Rear 30° (performance)
45° (recreation)
Super-Light or Extra-Light
Downhill Front 30° Light or Medium
Rear 30° Light or Medium


125 lbs / 57 kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Light or Medium
Rear 30° Light or Medium
Park / Pool Front 45° Super-Light or Extra-Light
Rear 30° Extra-Light or Light
Ramp Front 30° or 45° Extra-Light or Light
Rear 30° Light or Medium
Longboard Front 45° Super-Light
Rear 30° (performance)
45° (recreation)
Slalom Front 45° Super-Light
Rear 30° (performance)
45° (recreation)
Downhill Front 30° Medium
Rear 30° Medium


150 lbs / 68 kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Medium
Rear 30° Medium
Park / Pool Front 45° Extra-Light or Light
Rear 30° Light or Medium
Ramp Front 30° or 45° Light or Medium
Rear 30° Medium or Heavy
Longboard Front 45° Extra-Light
Rear 30° (performance)
45° (recreation)
Slalom Front 45° Super-Light or Extra-Light
Rear 30° (performance)
45° (recreation)
Extra-Light or Light
Downhill Front 30° Medium or Heavy
Rear 30° Medium or Heavy


175 lbs / 79 kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Medium or Heavy
Rear 30° Medium or Heavy
Park / Pool Front 45° Light or Medium
Rear 30° Medium or Heavy
Ramp Front 30° or 45° Medium
Rear 30° Heavy
Longboard Front 45° Extra-Light or Light
Rear 30° (performance)
45° (recreation)
Light or Medium
Slalom Front 45° Extra-Light or Light
Rear 30° (performance)
45° (recreation)
Light or Medium
Downhill Front 30° Heavy
Rear 30° Heavy


200 lbs / 91 kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Heavy or Extra-Heavy
Rear 30° Heavy or Extra-Heavy
Park / Pool Front 45° Medium or Heavy
Rear 30° Heavy or Extra-Heavy
Ramp Front 30° or 45° Heavy
Rear 30° Extra-Heavy
Longboard Front 45° Light or Medium
Rear 30° (performance)
45° (recreation)
Medium or Heavy
Slalom Front 45° Light or Medium
Rear 30° (performance)
45° (recreation)
Medium or Heavy
Downhill Front 30° Heavy or Extra-Heavy
Rear 30° Heavy or Extra-Heavy


225+ lbs / 102+ kg
Discipline Truck Geometry Spring Strength
Street / Freestyle Front 30° Extra-Heavy
Rear 30° Extra-Heavy
Park / Pool Front 45° Heavy or Extra-Heavy
Rear 30° Extra-Heavy or Super-Heavy
Ramp Front 30° or 45° Extra-Heavy
Rear 30° Super-Heavy
Longboard Front 45° Medium or Heavy
Rear 30° (performance)
45° (recreation)
Heavy or Extra-Heavy
Slalom Front 45° Medium or Heavy
Rear 30° (performance)
45° (recreation)
Heavy or Extra-Heavy
Downhill Front 30° Extra-Heavy or Super-Heavy
Rear 30° Extra-Heavy or Super-Heavy

Truck Axle Tolerance

Seismic axles (both G5 and Aeon) are manufactured to be 7.95mm in diameter, with a small negative-only tolerance. Racing truck makers who advertise “true 8.0mm axles” generally follow a similar specification. Average brands use 5/16-inch (7.9375mm) axles.

The inner race of standard wheel bearings has a diameter of 8.0mm, with a small manufacturing tolerance. Truck axles need to have a diameter slightly smaller than that, or else some bearings may not fit or even get stuck.

Truck Hole Pattern

Seismic trucks (both G5 and Aeon) support both “Old School” and “New School” mounting hole patterns. In the case of the G5, this was a significant engineering challenge given the truck’s unique structure.

The Old School mounting hole pattern has holes that are 2.50″ (63.5mm) center-to-center longways. In the New School hole pattern, that distance is only 53.5mm (2.11″). Both patterns have holes that are 1.625″ center-to-center sideways.


G5 Truck Mounting Advisory

Seismic G5 Baseplates have a unique structure and require full bottom surface support. Mount them directly onto the bottom of your deck, or else with stiff riser blocks between the trucks and the deck. Do not use rubber or urethane shock pads. These amplify stresses on the Baseplates – especially if the mounting bolts are over-tightened or tightened unevenly. Then relatively minor impacts can push the Baseplates past their breaking point.

G5 trucks will not fit through standard drop-through mounting holes, and they should not be drop-mounted to LDP bracket extensions. Unless extremely stiff riser blocks (preferably wood or even metal) are placed underneath the trucks, they should not be top-mounted on LDP brackets or on decks with drop-through mounting holes.

G5 Spring Truck Dis-Assembly and Re-Assembly

To dis-assemble a G5 truck: Place the board or truck upside-down, on the floor or a low workbench. Always pull off the Pivot Bolt Retaining Clip and untighten the Spring Tension Adjusters. Then press down on the hanger and hold while unscrewing the Pivot Bolt. (Note: If you don’t untighten the Spring Adjusters and hold the hanger down, Spring pressure adds resistance to unscrewing the Pivot Bolt and creates stresses that can damage the threads of the Baseplate Nut as the Bolt is removed.)

To re-assemble a G5 truck: Place the board or truck upside-down, on the floor or a low workbench. Always make sure to fully loosen the Spring Tension Adjusters. Otherwise much more pressure is needed to align the Hanger and Baseplate for insertion of the Pivot Bolt.

Set the Springs in the Baseplate with the sliding “piston” caps facing up. Place the Hanger on top, with the Spring Adjuster tips inside the piston cap sockets.

Press the Hanger down and hold it in place (using your bodyweight if necessary), to align the parts and keep Spring pressure off the Pivot Bolt. Then use a 7/32″ Allen wrench to press the Bolt through the truck and screw it into the Baseplate Nut. Fasten firmly, but don’t over-tighten. Sometimes a small downward push with the wrench helps the Bolt tip catch the threads of the Nut.

Always re-attach Pivot Bolt Retaining Clip after re-assembling truck. Replace Clip if it becomes bent.
Product modifications, including machining and use of non-Seismic components, are at your own risk.

If the Pivot Bolt unscrews only partway during disassembly and then gets stuck, the Baseplate Nut is probably stripped. To get the Pivot Bolt out of a stripped Nut, first place the truck in a vice (if possible). Pound the head of the Bolt back into the truck. This will force the stripped Nut out of its pocket in the Baseplate. Then slide a small flathead screwdriver (preferably #3) between the Nut and its pocket, or grasp the Nut with a strong pliers. This increases tension between the Pivot Bolt and the Nut, and it usually helps the Bolt cut through the Nut’s stripped threads. After unscrewing the Bolt, reassemble using a fresh Bolt and Nut.

G5 Spring Truck Noise

Seismic G5 Spring Trucks were engineered as a high-precision product, with virtually no slop in their steering articulation. So like a race car, they don’t dampen road vibrations much and may seem noisy compared to lower-precision trucks that use bushings. Some skaters are more sensitive to that than others.

Actual rattling noises can occur for a variety of reasons, regardless of the trucks you’re using. The most common cause is riding on rough surfaces with loose hardware and/or wheels that are too hard for the surface. In addition, bearing spacers can rattle between the bearings or against the axles if they’re the wrong size, or if the wheel core tolerances are off.

Try using softer wheels with properly-spaced bearings. Also check the fastening tension of your mounting hardware, wheel nuts, and truck pivot bolts. (Loose pivot bolts can also invite dirt and grime to gunk up the works, which in turn can lead to excess friction among the moving parts.)

The Seismic G5 technology itself was carefully engineered to eliminate squeaking, clicking and rattling, but a few seldom-seen issues can lead to these or other noises.

Most squeaking and clicking stems from friction between the small inner springs, the main outer springs, and the long-necked “sliding” spring caps. To reduce or eliminate the noise, try rotating the spring assemblies a quarter or half turn inside the spring chambers. (Loosen the tension screws first, then just turn the springs with your fingers.) After that, tighten the tension screws at least 1.5 turns. For added measure, drop a bit of silicone or graphite lubricant inside the long spring caps.

Finally, spring tension screws that are fully loosened may occasionally rattle inside the Seismic truck hangers, though ordinarily spring pressure keeps them quite still. Try tightening them 1.5 turns. This puts them in a “neutral” position where they function as intended. The trucks won’t feel stiffer when riding, but pressure from the springs will keep the screws from rattling.

Truck Wedging

The steering geometry of the Seismic G5 Spring Truck is absolutely fixed and perfectly consistent – either 30-degrees (Stable-Turn) or 45-degrees (Quick-Turn). The steering geometry of the Seismic Aeon Truck is also very consistent, especially for an RKP design. So wedged (angled) risers have a totally direct and predictable effect on their performance.

To quicken steering response, orient the wedge with the thin end facing the end of the deck. Usually called “wedging,” this is most commonly done with the front truck. Just remember this reduces your leverage on the G5 springs or Aeon bushings, so you might want to loosen them or even switch to softer ones.

To slow steering response, orient the wedge with the thick end facing the end of the deck. Usually called “de-wedging,” this is most commonly done with the rear truck, especially on racing boards. Just remember this increases your leverage on the G5 springs or Aeon bushings, so you might want to tighten them or even switch to stiffer ones.

Optimal truck mounting depends on many different variables – wheelbase, riding speed, skating style, personal preference and even body height. You’ll need to experiment to see what works best for you.


Seismic baseplates come in two geometries: Quick-Turn 45° and Stable-Turn 30°. For most boards, using a 30° truck at the tail and a 45° truck at the nose maximizes power, control, traction and stability. Exceptions: big vert, technical street and downhill boards (use 30° trucks on both ends) and low-speed recreational carvers (use 45° trucks on both ends)

Stable-Turn 30° baseplate & assembly

Quick-Turn 45° baseplate & assembly