Axle Needed For An Off-Road Utility Trailer With 40x13.50 Tires And A 8x170 Wheel Bolt Pattern

Updated 12/31/2024 | Published 12/29/2024

Question:

I’m modifying a utility trailer as an off road expedition type trailer. I am looking to use the same bolt pattern 8x170 and tire size 40x13.50 as my truck so I can carry one spare for everything. I wanted to use the timbren axle-less in the 5200lb with the long spindle and 4 in lift, but I see they limit tire size to 35x12.5. Is this just a suggestion or would they not fit? I know I will have to use a wheel adapter to get from 8x6.5 to 8x170. I’m not married to the axle-less option with 40’s ground clearance is no a big concern so if there is something that would be easier in an axle setup please let me know. Thanks!

asked by: Will

Expert Reply:

Hey Will,

The problem with the tire size is that if you go too large the wheels are going to rub the trailer. Timbren having done the math already and listing the maximum as 35 x 12.5 x 20 lets us know that you'd really need to make some serious modifications to the trailer to get it to fit and would still need a wheel spacer to go from 8x6.5 to 8x170.

Even though the Timbren axle-less system is great for off-road setups it just isn't designed for your larger tire size so the easiest option here would be to still go with a standard torsion axle setup. You would have to custom order the axles but that would allow you to compensate for the larger wheels by going with a larger hub face spacing. The cords inside of the torsion axle will help mitigate road shock and compression like a leaf spring but without the same fragility, which is crucial when off-roading. There's a build sheet that our customer service department can walk you through to order the correct axle(s) for your trailer if you give them a call at (800) 298-8924.

We don't offer a trailer hub with a 8x170 bolt pattern so you still would need to source a wheel spacer elsewhere to get all your wheels with the same pattern.

expert reply by: Kevin C

Axle Dimensions
(click to enlarge)

Will

12/31/2024

Kevin, Thanks for the response Kevin. I’m modifying an M1102 so the solid axle makes more sense anyway. I didn’t know the axle length could be custom ordered. That’s great since I’ll be able to dial in the width accounting for offset, tire width, and wheel adapters. Thanks for pointing me in the right direction! Will