Tire Size Question

Not riv related but I am wondering if I have 285s/75/r15s on my truck was size is it when changed in to like 30x9.5?

riviera2454 wrote:

Not riv related but I am wondering if I have 285s/75/r15s on my truck was size is it when changed in to like 30x9.5?

idk we had like 315/75?/16's on our 3/4 ton suburban and those were like 31 inches tall or so when i measured them

285's are around 11". not saying the rim is that big, it depend on how much it is bulging over.
285/75/15 works out to be 31.83 in diameter, and about a 8.5-9" rim width.

I have 275/35/18's on my firebird....

Quote :

Not riv related but I am wondering if I have 285s/75/r15s on my truck was size is it when changed in to like 30x9.5?

My buddy is running 275/65/17 on his trunk and the tires are 31" in di. I think the 275/65 referres to sidewall to footprint ratio so a 275/35 would be different height than the 275/65. I would check some of the tire websites to find out exactly how to measure.

BTY... I just put 33x12.5x15s on my Bronco today. HUGE improvement! Looks and stability...

first # - width of tire tread in mm
second # - percentage of the first # that determines the sidewall height
last #- the rim total diameter

if you want 30in total diameter then convert back to mm. (762mm) then subtract the wheel size (15in=381mm). take 1/2 of that you get 190.5mm. that is the sidewall size you need. now depending on how wide you want the tire to be you could have a 275/70R15 or 285/65R15 or 295/65R15. (295*65%=191mm)

all of those will change the total diam. to ~30in. which would mess up your speedo if the factory tire/rim combo has a different diameter.

hope that helps, i see i didnt really answer your question earlier b/c i didnt fully understand what you were asking for.