18" Wheel Questions - Anyone w/experience please read

[MXZDrew]

New to the forum, new to our 07' TCH. Loving both! Looks like a good group on here as well!

I just picked up a set of 11' Scion TC Wheels w/ 215/45/18 Yoko's mounted on them. I have a couple of questions on the subject. I have searched hard and thats why I went ahead with the purchase. I just wanted to verify and poll some users out there.

My main concerns are the following:

#1 - Those of you who did switch to 18's with this tire size, how bad of a MPG hit did you notice? I know there will be some as the wheel/tire combo are about 5lbs heavier each.

#2 - The TC wheels are 7.5" with a +39 offset vs. the factory 6.5" with a +45 offset. My calculations I ran say the wheel will stick out 19mm more. From what I have read, the car can handle an offset with a range of +35-45.

Can anyone confirm I will be ok with this offset? No harm to the driveline? I don't think they would rub even if I lowered which I do not plan on doing. Would you agree?

Sometimes when things are this close and all my searching provides no conclusive results then it's better to just try. I will be reporting hard facts as well as pics of the TC wheels on a Magnetic Grey 07' TCH which I expect will look pretty good!

[Chunger]

Given the same overall tire diameter and width (size). The TC rims would stick "out" an additional 6mm (45-39mm) assuming your numbers are correct.

My OZ 18" with old 245/40 ContiExtremes weighed less than the TCH rim/tire combo by about 1/2 lb each. MPG drop was like 1 mpg less due to rolling resistance probably... highly unscientific MPG figures, though, as it is hard to "have all things equal" (i.e. not a factor).

[pop11]

MPG will go down a little bit in city but wont effect much on highway.

[ukrkoz]

all you had to do is to read your manual. 18" inchers are said to drop mpg down by 1 mile to gallon. we had a discussion on this here not so long ago, and it was "no big deal" theme.
well, do your math. at $4 a gallon, divided by 37mpg average, it is 10.8 cent a mile. at 36mpg it is 11.1 cent. or, .3 cent difference a mile. personally, I drive around 2000 miles a month. that is 6 bucks difference a month, or $72 a year.

[arabianobsession]

Putting the TC rims on will be just fine. There are members on here with Camrys that put 20" rims on with no problems. And with any heavier wheel/tire combo, your gas mileage will suffer a little bit, but not by too much.

[Frodo65]

Originally Posted by ukrkoz

all you had to do is to read your manual. 18" inchers are said to drop mpg down by 1 mile to gallon. we had a discussion on this here not so long ago, and it was "no big deal" theme.
well, do your math. at $4 a gallon, divided by 37mpg average, it is 10.8 cent a mile. at 36mpg it is 11.1 cent. or, .3 cent difference a mile. personally, I drive around 2000 miles a month. that is 6 bucks difference a month, or $72 a year.

There's an additional dimension, that of tire life and replacement cost. The larger tire typically carries a considerable cost increase over the OEM tire, and the high-performance variants have significantly shorter wear life. Assuming 45K life for OEM tires, and $200 ea. replacement cost (Michelin OEM V-rated, $159 + $41 for shipping/install, UTOQ 460) vs $335 (Michelin HX MXM4, also V rated, $283+ 50 for shipping/install, UTOQ 300) and a 30K life.

Now, there are other choices that can drive the cost/life compromise in different directions - TR has a Michelin tire at $249 and a UTOQ of 500. But, for a comparable price/performance point, the larger wheel will cost more and won't last as long.