Rolling diameter of wheel& tire combo

[dmj]

Can someone verify the factory rolling diameter of the factory 15 in wheel and tire combo. I measured an evo with the 17 in wheel and 235/45/17 tire and it was just over 25 inches while my 18 wheel with 215/35/18 tires are 23.5 inches

 

[mooserage]

click Here you can input it yourself /ubbthreads/images/graemlins/smile.gif Btw, the rim itself is irrelevant, only tire size matters in overall diameter.
-shamus

 

[dmj]

Thanks just the info I needed

 

[belize1334]

Tire measurements are xx(width in mm)/yy(sidewall height in % of width)/R-zz(rim diameter).

The height is then the rim diameter plus twice the sidewall height which is expressed as zz + 2(xx*yy/100)/25.4 measured in inches. So the factory diameter is (15 + 2*195*0.60/25.4)" or 24.2". My 225/50/16 are slightly larger at (16 + 2*225*0.5/25.4)" or 24.9". IMHO you shouldn't run smaller than 24" 'cause it looks silly and you shouldn't go larger than 25" 'cause you could end up with rubbing issues if you have a lot of suspension travel.

 

So what would the correct plus size tire be for a 17inch wheel
If iirc you should always try to match the aspect ratio of the
original tire when you +1 or +2 at 195/60 for the oem tire you are
at 117mm logic would say then go to 225/45 or 235/45 or 245/40 but
all these are off from the oem aspect ratio. Am i missing something here?
I have a some 17x7 wheels 40mm offset but not sure what size tires to get
i know a 17x8 or 8.5 with a 235/245 tire would be ideal but i already have these
wheels and dont want to buy new ones right now any thoughts...

 

[belize1334]

You can't keep the same aspect ratio or you'll be way oversized. On a 17" wheel you want the sidewall to be in the 3.5" range. People have run everything from 205 to 245 on 17s and fit it in the fender well. You're gonna need it to be a 45 series tire if it's on the narrower size or a 40 series on the wide size. I personally am a big fan of 225/45/17 which puts you right at 25". These cars are low geared anyway and the fender wells are pretty big so I prefer to oversize when plus-sizing.

 

ok thanks 225-45-17 it will be for now then

 

[Whoodoo]

245/45/17 is a slight bit bigger diameter than stock on 8 inch wide wheels. That's what I've got and the difference is hardly noticable

 

[496of2000]

Here's a pix with 245 45 17". They sit flush in the rear and stick out a little in the front.

 

how wide is your wheel I would think a 245 would
be better suited for at least an 8" wide wheel.

 

[496of2000]

They are 17 x 8.