So we have 255/45 and 225/50 which number can we go up or down a little on? Can't get all 4 tires the same cause the first number is too different?

I really like those Eagle f1 all seasons and would love to put those all around without needing to buy a set of wheels or another set of fronts.

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

You can use 245-45-18 and you want Goodyear Eagle GT not Eagle F1 tires.

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Bright Red 2008 G8 GT

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if u dont like ur tires u should sell them to me

I'll sell you my fronts when I get a full new set. There the awesome falken 4152s or some number like that. Really nice dry traction, 0 snow traction.

So the 245-45-18s would fit on both front and back? Would that void any warrenty not being the exact size?

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Here's a cool tool to figure out just how much of a difference between sizes.
http://www.miata.net/garage/tirecalc.html

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GP's:04 GP GT, Past now G-Ma's Girlfriend's 97 GP GT, "Project Pink Power"

As long as the 245-45-18 tire is mounted on a 7.5-9" wide wheel everything will be ok.

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Bright Red 2008 G8 GT

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So it wouldn't work on the back then since fronts are 18-8 and the backs are 18-7.

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

I'm confused now. The front and rear wheels have a different setup? I know the width is different, but isn't everything else the same? As far as I know it is 5 x 115 bolt pattern with a 34 to 45 offset. I just want to make sure I have everything correct before I go and order wheels. My local tire shop doesn't have any that I like, so I'm going to just order them myself. When the check the Tire Rack, they won't list any for our cars. Can I just use a 2008 Grand Prix GT? As far as I know it is the same except for the diameter. I'm going with either a 7.5 or 8 x 18 with a 245/45-18 tire. I want a wheel that has black and chrome mixed in together.

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

2008 Grand Prix GXP

Front Tire Size: P255/45R18
Rear Tire Size: P225/50R18

Front are 18*8
Rear are 18*7

I still dont really have much idea what most of the numbers really mean lol. I just know thre rears are basically 1 inch thinner than the rears. Not sure why the 45 and 50 are different. Unless that is the width? haha, I'm so car dumb still.

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The second number (45 and 50) is the sidewall height in normal people talk
The first number is how wide a tire is in milimeters and the second number is the sidewall aspect ratio. So in this case for the 225/50 tire, the sidewall is 50% of 225mm, so roughly 112mm. Or for you silly imperial users, divide the mm number by 25.4 to convert to inches. So the tire measurements would be 225mm or 8.86" wide from widest point of the outer sidewall to the widest part of the inner sidewall (not always the wide of the tread surface itself) and the tire is 112mm or 4.41" high.

Tirerack has some great articles on understanding stuff like this.
http://www.tirerack.com/tires/tiretech/ ... ?techid=46

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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"

You can put 235-50-18's on the rear since that tire requires a 6.5-8.5" wide wheel. Then put the 245-45-18's on the front since those are 8" wide wheels.

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Bright Red 2008 G8 GT

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But I want the same size tire and wheel all around. They are both 5 x 115 bolt pattern on front and rear. But what about the offset? I need to know what I need to have the same sized rim and tire. I can do 7.5 or 8 x 18 rims all around with 245/45-18 tires.....correct? What is the wheel setup for the front and rear (offset, ect...) that I need to know to get rims?

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2008 Grand Prix GXP

The front & rear wheels have different offsets so they can't be switched. If you want to rotate the wheels & tires you'll have to buy new wheels.

You can try mounting 245-45-18's all the way around. A 245 width tire shouldn't be too wide for the 7" wide wheels in the rear, but you still won't be able to rotate the stock wheels because of the difference in offsets.

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Ok, I understand that.....bear with me Don.....but I'm putting on new rims also. So can I just go out and buy a set of rims that are 18 x 8 with an offset between 34 and 45 and they will work? The standard offset for a Grand Prix is 34 to 45. Is the GXP the same? Both front and rear? I guess I'm confused because my local shop checked on a set of rims from the tire rack for me that were 18 x 7.5, 5 x 115 bolt pattern, and an offset of 42mm and the tire rack told them it wouldn't work on a GXP.

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

2008 Grand Prix GXP

Do me a favor and sell me your fronts when you get new wheels. I'll even pay to ship them.

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

I could do that. I'll let you know.

-- Fri Feb 18, 2011 7:31 am --

Where do you live in Ohio? You could probably come and get them to save on shipping.

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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 I wasn't on the north east side I would lol. I'm lazy so I don't mind paying for shipping.

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This is what I got when I searched for wheels for your car at Tire Rack.

We're sorry. There are no wheels that match your current search criteria.

These are all the wheels that will fit from Discount Tire Direct.

http://www.discounttiredirect.com/direc ... 12528&fcb=

I know there are wheels that fit the GXP since some of the members have put them on their car. You can PM the guys that bought wheels for their car and ask them about the offset.

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Bright Red 2008 G8 GT

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Wow, it comes up on the Discount Tire site. Thanks Don.

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

2008 Grand Prix GXP

235/50/18 Fits all 4 stock rims without any issue and are only 0.9km/hr difference for speedometer... My winter tires are Blizzaks in that size currently on stock rims. That size will fit 6.5 to 8.5 inch rims, GXP is 7 inch rear, 8 inch front.

Should be easy to find some second hand as well since it's also the stock size on a lot of Mustang GTs. That's assuming you would be fine running the same size on all 4.

But I'm guessing your end goal is being able to rotate them ?

I haven't had any issues with strange wear on any sets of tires, the GXPs have double the negative camber that most other cars do for cornering (0.18 vs 0.09 if I remember correctly). So it's normal that all 4 tires will wear slightly more towards the inside. I had an alignment done at the end of 2008 on my '08 GXP at 20,000km (the passenger front tire had more wear on the inside than the others) and I'm at 62,000km now. The alignment was out quite a bit at 20k. I'm betting there's a break in period or the factory didn't do a great job on the alignment in the first place on our cars. My factory summer tires still have enough tread to run another season, but I will probably have the money to get new ones after winter anyways.

I've heard good things about the Kumho Ecsta LX (KU27), and there was a different tire my buddy recommended that I read really good things about a couple months ago. I don't remember which tire they were, I'll post here when I find out again... They were going to be 235/50/18 in the rear, 255/45/18 in the front for the other brand. At his cost they were about $580 for all four. I think about 800 at either 1010tires or tirerack when I was shopping last summer.

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2008 Grand Prix GXP Dark Metallic Grey

Good to hear about the Kumho's being good, because that is the exact tire I got. It had really good ratings and it's a 60,000 mile tire if I remember correctly. The tires and wheels are in, and they are installing the sensors on the wheels for me. All I have to do is have the wife get them put on. I won't be home for a couple more weeks:-(

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

2008 Grand Prix GXP

Just wondering if anyone has tried the hancook ventus v4es tires

I have them what im currently running. Have about 18k on them and still plenty of thead. I love the grip especially in the rain

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Thanks REDCOMPG