Don't waste your time or money on 3 peice wheels. I have done large amounts of research on this. If you want the long version see "last word on wheels". The short version is I have a black XLR which I put Foose Speedster wheels on in chrome. Everyone agreeds best looking XLR you will ever see. No matter what anyone tells you, put 19X8.5 on both the front and back with 45 off-set. The foose wheels are an off the self item and cost a fraction of 3 peice. Plus they look better. The tires you want are Michelen pilots 255X40. Again, there are a lot of reasons why, however this is the ONLY combination that will increase ride quality, handlings with no negative effects on the car.
I'm going to let you guys fight this one out. But for the record, I didn't agree to it either. Besides, how could it be the best looking XLR anyone has ever seen if you don't have a gold package? Lotsa proud pappas around here, eh?
BUDSVET - you seem to have the most mileage. Have you (or anyone else) worn out a set of tires yet? What kind of mileage can we expect on the first set of tires.
First of all I am not dissing anyones wheels. Just saying that your car will not look it's best with the ones you chose.
Second, by putting on 20" wheels, you have killed the ride quality, supension, traction control, speedo, braking capibilites, (do you get the picture or do I need to go on?) magna-ride, etc.... Basically, your car is not going to perform nearly as well as it should. You are also going to see excess supension wear because you are putting a far greater load out at the edges of the car. That's not good. I promise that you are also going to see a drastic decrease in brake wear.
You have to remember that this car is highly engineered. That engineering was done with 18" wheels in mind. You can change to 19", with a very specific tire and size without changing the engineering. However, anything bigger will!
I wrote about this in another thread, but here it is agian.
If you use the wheel & tire size combo that I reccomend (and there are others that will work) the tire preasure system will function perfectly. However, there is not a run-flat tire that will fit this size. However, there are some significant advantages to NOT having run-flat tires.
First, run-flat tires have significantly stiff sidewalls that reduce ride quality when compared to a non-runflat tire. Second, run-flat tires are much heavier. Taking that rotating weight off the car will noticiable increase performance (assuming you replace them with high-quality tires designed for this type of car).
Lastly, When was the last time you actually changed a tire? The corvette Z06 does not have run-flats. Chevy solves the problem by including a can of fix a flat! The XLR is equiped with on-star and road side assistance. Also, if you choose your tires properly, it just is not a problem.
I must say, you have me convinced. The research you've done is impressive. You must be an engineer (like me). If I can get a better ride than I'me currently getting with 19s, then that's pretty cool. I may consider it when the current tires need replacement. We'll see.
I went with 20s on my new Escalade because 22s have a reputation for riding rough. I didn't do the reasearch you've apparently done, but I know I do not like the standard wheels and tires.
All the same, I cant wait to see the photos of the Raven Black w/20" wheels and a gold package. :cheers
I also have 20" on my esclade. The standard wheel is boring. I am not formally trained or schooled in any sort of engineering, but I like working with cars as a hobbly and understand the basic principals involved.
The 20" on the Esclade are fine because of the size of the truck which has heavior brakes and supsension already. Also, there are a lot tires available the will help with ride quality. However, any bigger and you will need to upgrade the brakes!
If you like to drive fast, if you like to fish-tail, if you like to drift into turns, then I suggest you replace your stock run-flats with either F1 or P0 tires.
I took a right turn (with track/stabilitrack off) had a nice fishtail going, when suddenly the front, not the rear spun around, slammed on the brakes, anti lock activated, now I'm in an uncontrolled skid backwards, I skid for about thirty to forty feet BACKWARDS with the break pedal slammed to the floor, and did not stop till I hit the curve. Luckily there were no parked cars or traffic.
Damage: Bent drivers-side-rear tie rod. Bent Rim.
Special order - two weeks until I receive it. SOL until then.
I spoke to a tire dealer regarding this, he said that because run-flats have such thick side walls, they have absolutely no performance capabilities. And regarding the thirty foot reverse skid, his reply was that since I had been placing so much pressure on the tires, they had heated up to a point where the traction had all but been lost.
Conclusion - Unless you are over sixty, get rid of your run-flats and get your self some decent performance tires. I was going to wait till I wore out these tires but now I have no choice.
I already had special ordered the rims from IForged. Three weeks till delivery.