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Discussion Starter #3
Thank you Aviator.
I'm sure yours is just as nice. It must be the Southern California sun that helps my Dream Machine look so good. We all have a very unique vehicle and I don't know how you feel, but it looks good with the top up too. I will be going to the next generations XLR-V when it's available. I'm surrounded by 394 HP Mercedes's. Can't wait to kick some of their butts.
Bob
 
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Discussion Starter #5
Bill N,
I took the vehicle out with the original setup and then with the 20's and Michilen Pilot Sports and found it to be more glued to the road and especially with quick lane changes. If you think people drool over your XLR now, put some nice 20's on the car.........You'll think your a rock star, and so will everyone else.
 

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To 19 or to 20? That is the question.

standby said:
Bill N,
I took the vehicle out with the original setup and then with the 20's and Michilen Pilot Sports and found it to be more glued to the road and especially with quick lane changes. If you think people drool over your XLR now, put some nice 20's on the car.
The most remarkable thing about the XLR is the "un-roadsterlike" smooth ride, thanks to Adaptive Ride Control. A guy (Rick) on this forum swears in another thread that we should not go up to dubs, because it causes the car to ride too rough. He makes a case for sticking at 19s. For me, the magic of the XLR is performance AND comfort.

So how comfortably do those 20s ride? FYI - I also have a Torch Red C4 to drive if I want Houston's mean streets to smack me around while I'm going fast.
 

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I have 20s on mine and love the look (see my garage) and the handling.
It drives like a slot car!
I have my stock wheels back on again after a year, and while the
ride is much more comfortable, I feel a real lack of control,
and can't wait to get the 20s back on again.
As long as the overall diameter remains the same,
I don't follow Ricks argument , other than comfort, between stock, 19 or 20.
A shorter tire sidewall does have it's drawbacks though....
I had a little misshap.....80mph on the freeway....downed lightpole......


"Hello, On Star.......did you say four flats?"
 

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Eyedoc said:
Ouch!

Covered by insurance , I guess.

What type of wheels are those?
Makavelli, custom made
They are 3 piece wheels and only the inners bent and needed to be replaced
( the advantage of a 3 piece wheel) I also had one of the outers re-chromed that I scraped a curb
$730.00 plus 4 new pressure sensors @ $75 each


Insurance $1000. deductable
 

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1_XLR said:
I have 20s on mine and love the look (see my garage) and the handling.
It drives like a slot car!
I have my stock wheels back on again after a year, and while the
ride is much more comfortable, I feel a real lack of control,
and can't wait to get the 20s back on again.
As long as the overall diameter remains the same,
I don't follow Ricks argument , other than comfort, between stock, 19 or 20.
A shorter tire sidewall does have it's drawbacks though....
I had a little misshap.....80mph on the freeway....downed lightpole......


"Hello, On Star.......did you say four flats?"
My argument (and I wish I did not have to make it) is that bolting on a set of 20" wheels and tires causes more problems than just ride height. As you have found out the ride quality suffers. The other issues are safty and engineering. Your car was designed and crash tested with 18" wheels which were made to a strict tolerance by GM or thier supplier. Changing to a 20" not engineered to these tolerances causes problems when the car is crashed. It could be as much as the difference between walking away and having a crushed leg or worst.

The other factor is weight. When you move the added weight of a 20" wheel with the super stiff and small sidewall, you have changed the shock ratings which effects the ride and puts excess wear on the supension that it was not intented for. Also, the 20" wheels have a far greater rotating mass than the 18 or 19". That rotating mass can cause all sorts of problems because it is on the outer corners of the car. You can see problems like brake fad, excessive wear, longer stops, and under hard braking you could boil the fuild which leads to complete brake loss.

These and others are the reason why GM is on a crusade to educate people about all the pro's (basically looks) and the cons (everything else) of changing your wheels to ones not engineered for the car. There is a move currently underway to have all aftermarket wheels stamped with an ASE rating which would help the issus.

Lastly, I think a lot of people misunderstand my appoarch. I am all for changing and personalizing the XLR to the owners taste. I have modified mine. However, I take great care to ensure that the modifications actually improve (or at least do not hurt ) the car while also looking nice. That is the key to me. The reason why is that I have seen lots of aftermarket parts for all types of cars and most that I have purchased I have eventually been dissapointed in because they hurt the driveability of the car. I want to warn those who are considering the 20" wheels what they are really getting into fbefore they spend thier money.
 

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Sorry Rick, didn't mean to get you going on this again.

I put 20s on for the looks, first and formost, and I like feel and the handling.
Is it the best thing for the car? Probably not, I'm sure you know better than I and I may have settled for 19s had you originally posted prior to my purchase.
But there's always drawbacks with aftermarket products.

BTW
the run flats weigh a ton!
most any wheel combination without them is going to be lighter
 

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1_XLR said:
Sorry Rick, didn't mean to get you going on this again.

I put 20s on for the looks, first and formost, and I like feel and the handling.
Is it the best thing for the car? Probably not, I'm sure you know better than I and I may have settled for 19s had you originally posted prior to my purchase.
But there's always drawbacks with aftermarket products.

BTW
the run flats weigh a ton!
most any wheel combination without them is going to be lighter
IT's not so much how much weight total as where it is located. Basically the farther from the center of the wheel, the worse. Think of it like this. If you took a 20LB weight that was perfectly round and placed the front axil through it, the spinning wheel with the weight would not effect much. However, take the same round weight and bolt it out by the edge of the tire, and there is a hugh difference.

Another, and possibly better example is to watch a figure skater. When they put there arms straight out while spinning they slow down, but have a very hard time stopping. When the move thier arms in tight to there body, they speed up dramatically (less rotating mass at the edge) but are easly stopped. You can do the same thing sitting on a bar stool if you don't skate. Anyway, the same laws of pyshics apply. In other words, a little weight in the right places makes a big difference.
 

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No, I don't skate, and have been known to fall off bar stools
when they're not spinning (but the room is!)
but I get the idea, thanks
 

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Yikes!

1_XLR said:
Sorry Rick, didn't mean to get you going on this again.
Jiminy Christmas! You guys have been busy! I go away for a few hours and you're at it again!

1_XLR - sorry to hear about your mishap. I had a guy in a pickup back into my C4 on my second day of ownership. Put a nice impression of a trailer hitch right on the nose. Just picked it up from the repair shop today.

You see, standby, there's controversy in them-thar dubs. As beautiful as they are, Rick makes a convincing case for 19s. And he writes (and spells) like an engineer, so the physics are square with my BSME.

And I really like those rakish pipes. :thumbs

19s or 20s? Whatever the decision, I gave the car to my bride for her birthday in May. (still only has 4,500 miles) If the wheels and pipes just show up on the car, you think she'll notice? :) :angel :glol

Rick - thanks for your input as well. Your thoughtful insight is always welcome. I've just gotta do some new wheels and a cat back.....now how am I gonna sell it..... :confused

Aviator
 

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aviator said:
Jiminy Christmas! You guys have been busy! I go away for a few hours and you're at it again!

1_XLR - sorry to hear about your mishap. I had a guy in a pickup back into my C4 on my second day of ownership. Put a nice impression of a trailer hitch right on the nose. Just picked it up from the repair shop today.

You see, standby, there's controversy in them-thar dubs. As beautiful as they are, Rick makes a convincing case for 19s. And he writes (and spells) like an engineer, so the physics are square with my BSME.

And I really like those rakish pipes. :thumbs

19s or 20s? Whatever the decision, I gave the car to my bride for her birthday in May. (still only has 4,500 miles) If the wheels and pipes just show up on the car, you think she'll notice? :) :angel :glol

Rick - thanks for your input as well. Your thoughtful insight is always welcome. I've just gotta do some new wheels and a cat back.....now how am I gonna sell it..... :confused

Aviator
My spelling is the product of having access to spell checking software since 1980. I am so use to just getting it close and then letting the computer take over that I often spell things consistantly wrong. I guess I should run my postings through MS Word first.
 
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Discussion Starter #16
Rick,
We do appreciate your time in giving us the information on the changing of 18 to 20" rims. I'm sure you really believe you have this info wired, but this is more than once you have gone to the trouble of Boo Hooing 20" rims. We thank you for your interest in safety, but if everyone adheared to safety we would have never got to the moon.
 
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Discussion Starter #17
A trick I learned, was to type my message in Word, then after spell checking I cut and paste it into the message center.............just a thought
 
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