Thread: Good idea to swap 18X7 for 18X8?

I don't know about the fitment issues, but I do have a couple thoughts on what changing the rear tires will do. It add a lot of understeer into the car. This will make it feel like you are going faster at the same speed, and make the car more likely to plow. If you keep the fronts stock, it won't mess with traction control. It will mess with ABS cause they have different revs/mile, but it shouldn't hurt your stopping distance much cause you are adding tire and the front tires do most of the stopping anyway. Where you really suffer is when turning, and it will hurt ESC. You'll loose some g's going around corners, and when ESC kicks on you'll plow a lot more. If you are a straightline only guy, no biggie.

I do know that I'm going back to the stock tires next time I change them. I put Goodyear Eagle F1's on they really screwed up the traction control and ABS. I lit up the tires the other day, and they just roasted and I just sat there waiting for traction control to make them bite. Maybe the Potenza 960's will work better as an all season, I think Panther427 said he put those on. Anyway, my point is changing tires will screw up all the computer stuff way more than putting bigger tires on the rear will.

Understeer is when you hit the wall with the front of your car, oversteer is when you hit the wall with the back of your car. Power is how fast you hit the wall, and torque is how far you move the wall.

Unfortunately, I drive my GXP like an 80 year old man would (I'm 33). Several days a week I drive less than 7 miles per day and the hardest corners I turn are to pick up my daughter from school. It's a pretty simple ride for me. The last 2 full tanks I had an average speed of 22.4 and 22.8 mph, this tank won't be much different . I don't see how putting 18X8 stock rims on the rear of my car will make much of a difference.

Right, that's if you run lap times drag or drive it like a true performance car. This is just my daily driver that never takes a corner faster than about 2 mph. Don't get me wrong, I get on it when I can, but it's always in a straight line and for a very short period of time. My cars get very few miles put on them. If we go anywhere as a family we take my wife's vehicle and mine sits in the garage.

I was just trying to throw some info out there, not trying to discourage you from doing the mod. For your driving habits, changing the rears should basically have no effect. You'll never see a downside, and some of the stuff, like being more stable, feeling faster, and being able to rotate the tires, will be a noticeable upside.

Not a problem, I wish I was able to drive it a little harder but it usually just doesn't happen with what I drive for. I drive to/from work and pick up 1 kid from school. I had another car that was leased before this one that I had for 38 months and put about 22,000 miles on it. Needless to say, I bought my GXP. I don't think I even corner hard enough to spill a glass of water most of the time. At least I know the miles will stay real low on my GXP.

Just for ****s and giggles I swapped the 18x8's with the 18x7's for about a week and I had no trouble with rubbing in the back and the car handled and steered fine, granted I wasn't at the track at all, just daily driving. It did mess up the tire pressure sensors for a day but after a little while everything reset itself.

If you're just looking to get the same width rim all around for rotation purposes 18x8's would be better because you'd still have the wider tires up front for traction. It won't hurt you to go 18x7's either though. I have Monte Carlo SS rims with 235/50/18's for winter tires on the car now and have had no problems. Just depends on what your driving habits are and which rims you can find (18x7's) or (18x8's).

This is more good news. I've got 2 more 18X8 alcoas sitting in my basement and 2 more 255/45/18's on the way in the mail as I type. They'll be going on in the spring, can't wait.