Tire size
 

I have a 87 s10 blazer Tahoe addition. Will 29x10.50 r 15 fit on stock rims... It has 235/75/15 on it now. And I believe those tires will only be a inch wider

a little info for you:
235/75r15 translates in to the following

235= tread width in MM
75= sidewall height is 75% of tread width; known as Aspect Ratio
R15= Rim size 15"

so if we convert 235 into inches, which is 9.25", then we take that and figure 75% of it, which is 6.9", you can go from there to figure your tire size. your current tire is 9.25 inches wide and is 28.8 inches tall. to get the height you would take the 6.9" that is your sidewall height multiply by 2, for both sides of the rim, then add the diameter of the rim, 15 inches. 6.9 x 6.9 + 15 = 28.8

your stock rims are 15x7 i believe. i know that the ZR2's came stock with 31x10.5 on the same rims that came on 4x4's. you may have rubbing issues depending what your rig is.
a little more info next time, is it a 4x4? lifted? running aftermarket rims with different backspacing?

BTW, welcome to the forum.

Stock 87 4x4. 235s is stock size 29x10.5 are roughly same height just wider. I know what the 235 measures out to be just wondering if anyone out there tires that size on a stock non lifted blazer