Is There a Minimum Clearance From Trailer Frame or Wall Needed on Trailer Tires

Question:

Comparing something like a ST205/75D15 tire to a ST235/75D15 setup, the section width is something like an inch and a half different. If I want to move from a narrower to a wider tire, how much space do I need to ensure is between the tire wall and the wall of the trailer? Think of something like a covered trailer whose walls are designed to be light weight, not especially hardy. Is there a minimum or maybe maximum gap established by DOT or someone?

asked by: Jonathan

Expert Reply:

There is not a minimum or maximum width but you're generally going to want at least 1". Because the tires don't turn, you're not really restricted and may be able to get away with slightly less, but generally 1" is going to allow for sufficient tire flexion.

With that said, in comparing an ST205/75D15 like the # AM10245 to an ST235/75R15 like the # WST54FR, there is a 1.2" width difference and also a 1.8" height difference; you're not only adding a wider tire, but also one that is taller as well, so this would also need to be taken into consideration for any switch.

You will want to make sure that any switch in tire size leaves you with 2-3" of clearance from the top of the tire to the wheel well in order to prevent your tires from contacting the wheel wells when your suspension flexes. As long as you've got that clearance and your tires aren't rubbing on the trailer walls, you won't have any issues.

expert reply by: Erik B