I searched, but could not find any info on tire size 225/40/18's.

I don't want 215/35/18's. Not enought rubber for me.

I was thinking about 215/40/18's.

But what about 225/40/18's ? Is the rubbing much worse than 215/40/18's.

Any help would be greatly appeciated.

 

225/40/18 is too big, definitely don't go with that.

The first number is the width, ex. 225 = 225 mm wide
The second number is the height BUT, it's like this 40 = the height of the sidewall is 40 percent of the first number which is 225 so the height is 40 percent of 225.

Think about it that way and you'll understand that 225/40 is quite a bit bigger than 215/35

 

I'm really ____ed off at myself for buying 215/35-18 because everyone says they're the best but all my rims are f***ed up now. I have 215/40-18 and i only have a few scratches on my rear wheels. If the 225/40-18 don't excist definately go with the 215/40-18.

 

Look in the FAQ on this site to find the wheel dimension calculator, or google for it. You'll find out just much you're speed/odometer will be off with what wheels you pick. 215/40-17 are less than 1% off, so 215/40-18 will be too big. 215/35-18 will be closer, so a person has to live with the fact that huge wheels will likely take damage if driven around. Stick with 17s and you're life will be easier around town. Or add 5% to you normal driving speed and odo I guess.

 

besides tire size, I always look to see what the sidewalls of the tires look lke. Most low profile tires now come w/ a rim guard. The rubber of the sidewall sticks out just enuff to limit curb rash on the wheel.

I'm running 215/40-17 Nitto Neo-Gens on my xB, and 225/40-18 S-O3 Pole Positions on my Matrix Xr.

 

You might want to consider the size of 225/35-18 at 24.2 inches in diameter. Our fitment team has approved the 225/35-18's as an option to the 215/35-18's which are 23.9 inches in diameter. The 225/35-18's will give you a little more width, a little more height, and a little more protection for the wheel lip!

roger@tirerack.com
Sales Representative
Moderator www.scionlife.com To place an order please call 877 522 8473 Ext. 627 or for internet orders through www.tirerack.com, please mention my name in the previous contact field directly above the Place Order button on the Order Summary page for quick, efficient & professional service.

 

WOW, I guess we now have Roger to thank for our tire tech questions. And thank you for sponsoring a forum on Scion Life! I guess I know who to see now!

 

Being that not everyone has an automatic tire calculator handy from their desktop no matter where they're at.... it's better if you just memorize the formula so you can figure it out wherever you're at (tire store, magazine rack.....) It's really not as complicated as it seems


To figure ROLLING DIAMETER (that's ACROSS not AROUND!)

tire width x aspect ratio / 25.4 x 2 + wheel diameter = rolling diameter.

*BREAKDOWN EXAMPLE* a 215/35 - 18 setup would look like ~~>

((215 x .35) / 25.4) x (2) + 18 = 23.92"

FACTORY WHEELS/TIRES would look like ~~>

((185 x .65) / 25.4) x (2) + 15 = 24.46" (1/2" larger than first example - roughly 2.5MPH faster than 215/35-18 's, well within calibration of the speedometer)

Keep in mind that as tires wear, they change nearly an INCH in diameter from the time they're new to old. One inch of extra rolling diameter equals roughly 5MPH decrease on the speedo. ROUGHLY. Not an entirely bad thing as tires wear, you actually start going a little slower than you think you really are.

Problem starts when you begin Plus-sizing tires, otherwise if stock is 23.92" and you're doing 65MPH. You go up to 24.92", speedo says 65MPH (BUT!!) you're actually doing 70MPH.

 

Don't go by the numbers alone. I have had 3 sets of 225 40 18 on my 18X8 RacingHart rims and every set was different from each other. I don't recall what brand was the bigger tire, but not all 225-40-18 tires from different manufacturers will have the exact same sidewall. Just like tire ratings, a 340 threadwear on one brand might be the equivalent of 280 threadwear on another brand.
I have 225 40 18 on my 18X8 rims and that's the smallest tire I think anyone should fit on an 8" wide rim. If you have 18X7 or 7.5 then 215 will be OK.

 

Tire calculator:
http://www.discounttiredirect.com/di...foTireMath.jsp

Is it silly of me to suggest ... going to a smaller rim *gasp*? Maybe 215/40-17? Just a suggestion... :D