I bought the Yokohama AVID ENVigor tires for the GXP. They are the stock size (can't rotate) and after 12,000 miles, the car sounds like a semi truck going down the road. I took it to the place where I got the tires and they said the tires were "cupping" due to non rotation. I find it hard to believe that this can happen after 12,000 miles. I got 40,000 miles out of the Bridgestones that came on the car and they were still ok. I only changed them because they were not good in the winter. So, I've sent an email to Yokohama to see what they have to say. So, if you are in the market for tires, I would not recommend these. If I don't get any help from Yokohama, I just might buy new rims and tires this summer that are all the same size so I can rotate them.

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

I had Kuhmo's that started cupping after 1 summer... And I rotated them at every oil change. Someone told me it could be a bad inner belt that broke in the tires..

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I had the same tires and had the same problem. I am now running Pontenza Pole Positions (the "all-season" version of the OEM tires). So far, so good.

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I'm at 37k and still have the stock rear tires on. I had to change the fronts only due to alignment damage. Maybe try unidirectional tires? Since we can't rotate them anyway.

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http://www.cardomain.com/ride/3882088

How much did those Pontenza Pole Positions cost you? Yes, I was thinking of doing the unidirectional tires also. I will have to look into costs and see what I come up with.

-- Thu Feb 10, 2011 12:48 pm --

If I do decide to go with a different rim all being the same size, what is a good size for our cars? Do I go with one that is the same as the rears?

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

if you go with a non directional tire you can swap them from side to side at least, and that will let the tire spin the other direction and should fight the cupping..

as for rim size get what you want.. the front tire/rim combo will fit the rear.. too..

and remember too that if you get directional tires you can only swap from front to rear as they must allways spin the same direction

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2001 white gt coupe with enough crap to make it run mid 13's with 3 bad pistons
2002 40th GTP sedan mostly stock

Pretty sure they were 25-30 dollars more per-tire than what you purchased. They handle pretty decent in snow (have yet to get stuck here in Chicago).

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You can go 18x8 all the way around. You could get another set of stock 18x8's as well.

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

Well, Yokohama is going to give me 35% of the purchase price. Not great, but better then nothing. So I'm going to check into getting new rims and tires together all the same size. Does anyone know why the front tires on these cars were wider? I just don't want to get anything too small if it has anything to do with weight distribution. But, I thought these cars were not much heavier then the V6 version since we have aluminium blocks in them. Or is it just for more grip? I'm surprised they didn't go with the wider tire all around.

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

From what I remember reading it had all to do with torque. Same reason why like older muscle cars had big back tires. To compensate for all the extra torque and keep you going straighter. I think thats why most people buy a new set of stock fronts and throw them on the back, which i plan on doing before I get new back tires. I remember somone posted a link to a site that had a bunch of older car wheels like ours and the bonneville and other GPs.

I was wondering is getting the front wheels for the back going to make them stick out further or in furthers? I noticed the part that actually connects to the wheel hub is a different length, but I don't remember which side was longer.

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http://www.cardomain.com/ride/3882088

from what i remember the front are wide for performance and the rears are smaller so the car has a more "neutral" feeling too it.. to keep the grip the same front and rear. more weight in the nose and less in the rear so they put tires that would grip ''equal'' front and rear, at their respective ends.. meaning if wider tires are put on the rear the rear could have more tractin than the front causing "push" in corners when at the limit.. the factory did this to be a bit more perdictible and make driveablity under performance better


bottom line is as long as you know what "could" happen and dont drive with your head up your ass, it is irrelivant as the acctual difference is minor anyway

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2001 white gt coupe with enough crap to make it run mid 13's with 3 bad pistons
2002 40th GTP sedan mostly stock

Post #6 has pics of 18x8 stock gxp wheels. Again this is if you want to stay with the stock wheels. I would get 18x8's all the way around unless you are looking to go bigger like 20's.
http://www.grandprixforums.net/gxp-18x8 ... 37370.html

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1999 GT|SLP CAI|Borla Catback| Shift kit|18" Koblenz|GMPP Lowering|GMPP handling|Blk Headlights|ER Rcokers|HV3|HV TB http://www.fquick.com/The_Guz

I put Goodyear Eagle GT's on my G8 and I love them. They have great dry/wet/snow traction and handle fantastic in the corners. They are smooth and quiet after 15,000 miles with no sign of cupping.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
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http://www.midwestwheelandtire.com/sear ... &year=2007

Found that website that sells our wheels. Not sure about the price tho... I still deffinatly plan on picking up a set of the fronts.

Maybe someone on here would want to swap my rears for their fronts knock out two birds with one stone.

http://www.wheels-and-rims.com/cgi-bin/ ... 1607543.22
a bit cheper here but they are all reconditioned. $20 shipping

http://www.finishlinewheels.com/PONTIAC ... -06592U80/
Cheapest so far. $18 dollar shipping


I'm going to keep looking around.

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http://www.cardomain.com/ride/3882088

Just put the Eagle GT's on the GTP in January. These things gave the GP new life. I'll probably replace them with more GT's when the time comes.

I'll say this too, I was laughing at BWM 745's that couldn't climb hills that had 3-4 inches of snow.

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There not available in either of our tire sizes for the GXPs.

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http://www.cardomain.com/ride/3882088

You can go with 245-45-18 in the front and rear. That size is available in the Goodyear Eagle GT's and is only a 1% difference in overall diameter compared to the stock sizes.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

Hey Don, could I just go with the 245/45-18' tires on the different sized rims and also rotate the tires front to rear? Would the tire look different on different sized rims?

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

Sure you can rotate the tires front to rear, but you would have to demount/remount them on the wheels. The tires will look a little different since the wheels are different widths, but it won't be that noticeable. You're only talking fractions of an inch difference which isn't much.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website

I thought the front rims would fit on the rears. Why do I need to dismount the tire? Sorry if this is a dumb question.

-- Tue Feb 15, 2011 7:24 pm --

Also, I looked into the Goodyear GT's and they are not rated for the front on the GXP. I think the tire has to have a 99 rating on the front and those only have a 96. They would probably work ok, but if anything went wrong with the tire, they wouldn't have to warranty it.

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

As far as I know the rear wheels won't fit the front of the GXP because the offset is wrong and they won't clear the brakes. As for the load rating, you don't drive around all the time with max weight in your car so they will be fine.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
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so you can get a tire thats not the exact size as the wheel?

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http://www.cardomain.com/ride/3882088

Yes, within reason of course, unless you want to be a part of the "stretch" club.

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Dubs:00 VW GTI VR6, Low and Slow 91 VW GTI 8v, Shave the Bay!! 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's Girlfriend's 97 GP GT, "Project Pink Power"

No I just want some good tires for my car. Eveything available blows in the winter.

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http://www.cardomain.com/ride/3882088

Wheels will accept more than one size tire as long as it's one size or two bigger or smaller. The Eagle GT's are great in the winter, I've run them on my G8 for the last 3 winters and I never have any problem in the snow.

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Bright Red 2008 G8 GT

Mods: DRCUSTOMPARTS Center Gauge Bezel
Superchips ECM/TCM Tune- Volant CAI
Solo Axlebacks - HID's
Holden V8 Badges
My Website