Tire size question

[John O from Jersey]

This might sound silly, but,,,,,

I'm running 235/85's on 16" rims right now but I have no spare. (Scares me every time I leave town). I'm looking for a reasonably narrow spare (it will sit on the hood) that I can mount on one of the many 15" stock rims I have laying around.

What narrow 15" tire size would come close enough to the diameter of my 235/85 16's?? I'll be reaching out to local tire shops to maybe even find a used leftover.

Thx

John O

[siii8873]

The tire designation is tire width (mm), height % of width, and rim size.
So for a 235/85/16 the tire is 235 mm wide (mm/25.4=in) thus 9.25 in wide.
Height is 85% of width thus height= 9.25 * 0.85 = 7.8625 or ~8 7/8"
Therfore total height is 16 + 2*8 7/8 = 31 3/4

You would need to check 15" tire availability and get one that calcs out at this height.

Get another 16" rim would be a better option.

[cousindave]

IMHO go with a 16" rim and same size tire that way if you do get a flat you can keep the spare on and use the repaired tire as the spare.

[Lord Icon]

http://www.tyretown.com/my_sizecalc.htm
Everything you ever wanted to know about tyre sizes and ratios ...

[yank]

33x9.5x15 is close.