Originally Posted by mario4r

When to install new tires I had ordered a lift a couple days before I told the tire guy if they could put the spacers since they were going to mount the new tires.. He said they cant do it because spacers are dangerous a wheel could fall out or it could vibrate or affect the truck in the long run..

Is this true??
How long before you check on your spacers to see if they are well bolted on??

Sorry im new to spacers..

Originally Posted by TRD Pro

Other than the slight tire rubbing they cause, my Spidertrax spacers have been trouble free for the last 8000 miles since I installed them. Here is an interesting write up I found from a guy on a Jeep forum.


"I recently installed a set of 1.5" Spidertrax spacers. However, prior to doing so, I took one of them, along with my spare wheel, into our engineering lab.

We modeled both in 3D using the latest NX CAD software. We did this by reverse engineering. That means taking all dimensions and determining the materials.

We identified the wheel material as alloy 356-T6. The spacers are made from 6061-T6 alloy. 356-T6 has tensile strength of 30,000 PSI. 6061-T6 has a tensile strength of 45,000 PSI. This means that in reference to the basic materials, the spacer is 50% stronger than the wheel for a given thickness, and the spacer is much thicker in section.

We ran an extremely complex finite element analysis of both to determine where peak stresses are and where each component is most likely to fail. The result is what I expected. In short, spacers are not the weak link. The wheel itself is 2x more likely to fail under severe loading than the well designed spacer.

Now, let me qualify our findings. Our corporate engineering team has designed significant portions of the Airbus A350 landing gear system. We engineered the latest landing gear system for the Boeing CH-47. Our hardware is on the F-35, F/A-18, F-16 and a number of other aircraft.

This same engineering team has analyzed the Spirdertrax spacers and concluded that they are extremely strong, stronger than they need to be. Over engineered. These spacers are utterly safe if installed properly. Like an offset wheel, they may accelerate bearing wear, but the offset is so little as to be of no great significance.

I installed the spacers very carefully. Not knowing specifically what brand and type of threadlocker compound was provided with the spacers, I tossed it and used Loctite 271 Red. Each spacer was torqued to recommended specs in a star pattern. The wheel was then installed and torqued to 95 lb/ft.

After about 150 miles, I pulled off the rear wheels and checked the spacer lug nut torque. No change... I'll re-check torque at each tire rotation.

Installed correctly, Spidertrax wheel spacers are not only safe, they're stronger than the wheels you bolt to them."

I didn't mention that we found areas of stress concentration in the factory wheels. We were able to pinpoint the most likely location of failure. I'll explain where that is...

The Factory Moabs have spotfaces milled into the wheel hub to provide clearance for assembly washers used during manufacture to secure the brake rotors on the hub prior to final assembly. Using an endmill, each lug hole is spotfaced on the inside (think of a spotface as a shallow counterbore). The edges and corners of these spotfaces are quite sharp. This is where the FEA predicted the greatest concentration of stress. Unfortunately, this is also adjacent to the where the studs transmit all rotational torque into the wheel. The failure to radius edges and corners is what leads to stress concentration. If your Moab is going to fail at the hub, it will crack at a spotface.

In short, Tom and Eddie at Spidertrax have designed and engineered a very high quality spacer, that if properly installed, will provide you with many years of problem free and safe use.

Originally Posted by JeffMerr

I think a lot of the fear of spacers comes from one or two horror stories that have made their way around every off-road forum. I believe the one I read the guy had them installed incorrectly. When you think about it, there are thousands and thousands of spacers installed on trucks all over the U.S. and there are very few stories of them failing. Good spacers aren't expensive so I really don't understand why people go cheap and order off eBay when it's something that important.

Originally Posted by Shaolin

I wanted to purchase some spidertrax wheel spacers not too long ago, but after all the surgery that needs to be done to prevent rubbing (cutting the fender liner, removing mud guards). I decided to wait it out and purchase wheels with the proper offset and tires.

Originally Posted by Jetboy

Be careful in replying on the jeep guys analysis.

What's important to remember is that the fasteners are only there to provide clamping force. Not resist rotation. And wheel failure from adding spacers is generally am issue of friction failure and wheel spinning against the hub. So the real issues are whether the spacer material has a lower coefficient of friction against either they wms or the wheel, whether the spacer is compressible under the force of the fastener, and whether adequate thread interface remains. All of these depend on the starting point and the spacer thickness and material.

For example aluminum spacer between steel wheel and wms likely makes it marginally safer. But steel spacer between aluminum wheel and steel wms is less safe. Anodized spacer is less safe than raw aluminum. And many other variables.

The FEM analysis seems misplaced to me. I don't think they really understand how fasteners work if they are looking at static failure. I wouldn't put much value in that analysis. In fact id put it in the category of engineering nonsense. Is analysis of the wrong problem and does nothing to indicate whether spacers are safe or not. That's simply not how they fail. Please don't rely on that for much. It's not wrong per se. It's simply not useful.

For me, I would buy a proper wheel for what I want. Unless there's a very small - 1/4 inch space needed for something like clearing a caliper or a remote resirvoir can then I might use a spacer. At some point your really stressing the hub, ball joints, and wheel bearings to much for long service life. On my trail rig with 12" wide wheels and 2" back spacing I know I'm dramatically shortening the life of the bearings but it's not a daily driver so I don't all that much care. And it weighs 3000lbs on big axles. On my 4 runner I wouldn't want to push the bearings that hard. They aren't very big compared to something like a land cruiser. And I've had a few failures on my last mini truck that used similar size bearings.

So I would suggest keep em small. Keep them uncoated. And check your torque a few times after installing.

Originally Posted by Jetboy

Be careful in replying on the jeep guys analysis.

What's important to remember is that the fasteners are only there to provide clamping force. Not resist rotation. And wheel failure from adding spacers is generally am issue of friction failure and wheel spinning against the hub. So the real issues are whether the spacer material has a lower coefficient of friction against either they wms or the wheel, whether the spacer is compressible under the force of the fastener, and whether adequate thread interface remains. All of these depend on the starting point and the spacer thickness and material.

For example aluminum spacer between steel wheel and wms likely makes it marginally safer. But steel spacer between aluminum wheel and steel wms is less safe. Anodized spacer is less safe than raw aluminum. And many other variables.

The FEM analysis seems misplaced to me. I don't think they really understand how fasteners work if they are looking at static failure. I wouldn't put much value in that analysis. In fact id put it in the category of engineering nonsense. Is analysis of the wrong problem and does nothing to indicate whether spacers are safe or not. That's simply not how they fail. Please don't rely on that for much. It's not wrong per se. It's simply not useful.

For me, I would buy a proper wheel for what I want. Unless there's a very small - 1/4 inch space needed for something like clearing a caliper or a remote resirvoir can then I might use a spacer. At some point your really stressing the hub, ball joints, and wheel bearings to much for long service life. On my trail rig with 12" wide wheels and 2" back spacing I know I'm dramatically shortening the life of the bearings but it's not a daily driver so I don't all that much care. And it weighs 3000lbs on big axles. On my 4 runner I wouldn't want to push the bearings that hard. They aren't very big compared to something like a land cruiser. And I've had a few failures on my last mini truck that used similar size bearings.

So I would suggest keep em small. Keep them uncoated. And check your torque a few times after installing.

Originally Posted by BlackWorksInc

It seemed to me that the FEM analysis simply assumed a set of properly installed SpiderTraxx and tested them accordingly. Theoretically if they were installed correctly then the SpiderTraxx should not rotate at all and be a solid component of the hub and wheel; so load forces and stresses should translate into the wheel. Granted I imagine they didn't bother to mention shearing forces on the studs because the studs were equal to or greater than OEM units and thus would have similar failure points at a shearing level.

Now it would have been interesting to see some testing with loose, slightly loose, or improperly installed units to get an idea of how they fail.

Originally Posted by marshal

I'm going to throw a curveball at you

DUALLY TRUCKS COME WITH A FACTORY 6" WHEEL SPACER IN THE FRONT

of course they're safe, just buy good ones.