Tire size. Profile / sidewall differences

[6.0L rice eater]

I have 245/40/18's on the car now and im about due for some new tires and i want to go wider in the rear. will the sidewall of the tire change with the width? as in if i have 245/40/18's now and go to 265/40/18's will the sidewall be bigger. and if so will 265/35/18 be around the same size as a 245/40/18?

[Dreamcastin]

the middle number is a percentage of the first number. a 245/40/18 and a 275/35/18 will have the same amount of sidewall. a 265/35/18 will be slightly shorter than your 245. it will be the same height as 235/40/18s. hope this helps you

[zowwiewowwie]

This should help you out

http://www.miata.net/garage/tirecalc.html

[jmasse]

Both previous posts were accurate, but because of differences in manufacturing, you should look at the actual section width and overall diameter of each tire from the manufacturers website.

Example:
265/35/18 Michelin Pilot Sport
25.3 Overall Diameter
10.5 inches section width

265/35/18 Bridgestone RE050A PP
25.2 Overall Diameter
10.8 inches section width

The same differences can occur from tires from the same manufacturer, so simply look at the specifications on their websites.

I hope this helps.

[6.0L rice eater]

awesome. thanks alot.
im gonna go wiht the BFG KDW 2's
with 265's in the rear and 245's in the front

[Beach Goat]

You're in FL, get the KDs, the summer tire. Very grippy, awesome handling and traction. More so than the all season tires.

[Superman]

Try this site too:

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

(miata site came up red X for me)

[6.0L rice eater]

ok so i cant decide on 265/40/18's or 275/35/18's
will 275's even fit on the rear?
i have drag bags already

[zowwiewowwie]

keep in mind that the kdw runs a little wide

[Doric]

This should help you out

http://www.miata.net/garage/tirecalc.html
Yes. Thank you. I knew the second I saw this thread that this link would need to be posted.

[6.0L rice eater]

i have fit 245 KDW2's in the front before. im just trying to figure out a good size for the rear

[Spider-Man]

not to steal a thread but i have a question about the 245s. i just purchased a set of stock 18s and and having them powdercoated and need to wrap them in some rubber. i was thinking about going with what you had set up, 245 40 18 bfg kdw2. i know from the tire size calculators that there isn't much difference with the stock 17 setup, 245 45 17. did you have any issues anywhere with rubbing and whatnot? what is your suspension setup? mine is completely stock, pedders street 2 or track 1 in the future. any help would be great, thanks.

[svede1212]

i think you may have a problem getting 275/18 BFGs in the back without rolling or cutting the fenders. as said BFGs run wide anyways and not all goats are the same due to rear cradle alignment and suspension

[zowwiewowwie]

not to steal a thread but i have a question about the 245s. i just purchased a set of stock 18s and and having them powdercoated and need to wrap them in some rubber. i was thinking about going with what you had set up, 245 40 18 bfg kdw2. i know from the tire size calculators that there isn't much difference with the stock 17 setup, 245 45 17. did you have any issues anywhere with rubbing and whatnot? what is your suspension setup? mine is completely stock, pedders street 2 or track 1 in the future. any help would be great, thanks.

The 245 KDW2s that I had mounted up were real close to strut rub, but no rubbing. Any bigger and they wouldn't have fit.

[bigmanGTO]

Same here, they were very close, I just went back to 235's. Sucks.