Stock tire size

Hey Guys,
Can anyone tell me what the factory stock size tire is. After searching the forum the best I can figure out is somewhere between 28 and 29.5. I wanted to do some distance/speed calculations per rotation with different tire sizes. Thanks,

 

I decided to just use 29, it should be close...
I was wondering about my actual gas mileage and my speed reading on my speedomiter, and how off it was with bigger tires, Here's what I found out.

using 2*pi*r
with 29 inch tires the circumference is 91.1''
with 33 inch tires the circumference is 103.7''
thats a diffence of 12.6'' per rotation of the tire

one mile is 63360 inches
so, a 29'' tire rotates 695.5 times to travel a mile.
a 33'' tire will then have traveled 8739 more inches with the same number of rotations

this means that ever 7.25 miles the odometer reads, the bigger tires will have carried you an extra 1 mile.

Its just a way feel better about my gasmileage, it this is true, than I'm getting closer to 13 mpg rather than 11.

it also tells me that when my odometer says I'm going 45, I'm really going closer to 52.

if anyone notices any errors, pease tell me.

(disclamer: results are depending on wither the stock gears are still in place, both with the odometer and the drivetrain)

 

Since the circumference is proportional to the radius, you can just use the ratio of the radii (or diameters) to make your calculation.

From 29" to 33", you will travel 33/29 = 1.1379 times or 13.8% further. By your calculations, (7.25 + 1) / 7.25 = 1.1379. Checks out fine.

45 * 1.1379 = 51.25 mph.

 

AFK,

My '57 CJ5 has the original 7:00x15 spare on it, I believe, and it is exactly 29" in diameter. Good call.

The M38AI had 7:00 x 16, but thats another story.

Pete