I'm building a new tire carrier and mount for Hi-Lift, PullPall and Jerry cans for my RockHard bumper. I've got 35's now but will probably go to 37's in the future. I need to know the exact diameter of a 37" KM2 when mounted as a spare. I need to know how far apart to put my Jerry can holders so I won't have to modify it when I get the 37's.

Thanks

 

According to B.F. Goodrich's website, they are 36.8 inches in diameter on a 17 inch wheel.
37x12.50R17/D 36.8 Diameter

 

Thanks for the info. I've seen some discrepancies in tire sizes before and was hoping somebody running them could measure thier spare. I suppose there is not a snowballs chancein Hades that they would be larger than 37" so it would probably be safe to use 37". I know my 35's are 1/2 smaller than 35". The claimed 36.8 you mentioned is a tad smaller so 37" plus about 1/2" fudge factor would probably work.

 

Tire height and section width is also dependent on wheel width. The manufacturers measurements are done with a specific wheel width and using a smaller width wheel will increase tire height by .4" per every inch less of wheel width than how the tires were spec'd. If your intent is to run these on an 8" wheel, you'll likely end up with a 37.5" tall tire.

 

I believe that the 36.8 spec is on a 10 inch rim. The tire is shown being able to use an 8.5 to 11 inch wide rim, the 12.50 section width is shown while being on a 10 inch rim, so the diameter is probably for that width also.

 

I'd just put the cans 41" apart so you don't have to modify it later when you move up from 37's to 40's!

 

I'd be running them on AEV 8.5" rims. Does anybody have the 37" KM2 on 8.5" rims?


So you're planning on making my wife about 4" taller? I don't know about going to 40's. Yeah it would be nice, but (there is always a but isn't there?) it seems to me that 40's demand Dana 60's and a lot more engine. And I'd probably want to go to an AiRock suspension so ride height could be varied.

 

If the stated manufacturer height is 36.8 (which is nearly always correct when using the same size wheel width as measured and most people with surprises aren't using the static wheel width) and the static wheel width is 10", Subtract the wheel width difference, in this case being 1.5", multiply by .4 giving you an additional .6 inches of additional tire height. That number is going to be within ± 2% accounting for manufacturing variance, slight differences in wheel width and differences in air pressure. Having someone else measure the same setup is just going to add the additional variable of tread wear.

 

I guess I'll go with a spacing of 37 1/2" to 38".