i jsut bought some 17'' wheels and i am wondering the widest tire that i will be able to fit on my 00 gt coupe without rubbing?

9'' or 245mm

45 series tire would probably be the widest I personally would go. Some other memebers can back me up on this, your ride quality definetely takes a hit when you put the low profile tires on. This is easily offset by the looks though.

Depends partially on how wide the rim is... I've got 17x8" rims and 255/45/17 rubber... If I had stock suspension I doubt I'd rub that much if at all... with the B&G's on there I only rub if I hit a really big bump or have a ton of weight in the car... I could roll the fenders and not rub, just haven't done it.


Edit: corrected my typo... sorry just noticed it when RD_GTP03 pointed out the odd sizing.

Some of it depends on the offset too.

My wheels have a funky offset so they hang out a little bit. It might not be enough to fit a wider tire in there, but maybe it is....

Hey Guys...with some 5x114.3 - 18x8 - 38 offset, what would be the Perfect tire size, if I chose some 255/ ? /18...at the rear? I wouldn't even consider 255/54's as "SlickGTP"...as I Seriously doubt, those would even fit...since I am buying 18's...& I Never knew that there were Tires listed at "54"...maybe, He meant "55's" but, on the Other hand, what do I Know?

But, would I have to go more like 255/40/18, or maybe 255/35/18...to fit them under the rear?

And, just to make it Clear...Yes, it will Only be for Appearance & possibly Stability, I am Aware of the Fact...that the GP is a FWD, but I just Think that it would Really look Awesome!

The Front of course...would be Fitted with some 235 or, 245/40 or 45/18's. I am Thinking 235 maybe more appropiate, Thought...so can Anyone Help Me solve that Dilema? I have just been Thinking about that for sometime, after someone else here mentioned that they were rolling on 255's.

Now, I realize that, it's No Real Serious Issue...but, I would like to have this all Figured-out before the Spring arrives. And, I Think I would Trust You Guys Opinion, more so...than most of the Venders on-line, or local.

So, let me know what You Think/Know...& if You Think that I am Crazy, it's Ok! You may say that Too...No Hard Feelings!

There's a typo... Should be 255/45/17

With an 18" wheel you're going to have to shorten the height ratio to keep your spedometer acurate.

www.tirerack.com has calculators to help figure those sorts of things out.

the 245/45/18 is virtually the same height as the stock tire. www.bigwheels.net also has the info on each tire size listed in "mm" so you can easily compare tire heights.
Putting wider tires on the back for looks I dont think is such a bad thing, its just that you dont really have a lot of room to play with...too much wider or taller puts you in close to the strut lower spring pad...less offset will buy you some space there but then it moves the tire out far enough to contact the fenders when you run over dips and bumps.

When Pontiac first released the GXP, it was equipped with narrower tires in the rear to try and help offset the FWD natural tendency to understeer...so wider in the back will look better but create more rear grip, making it easier for the front end to "plow" in hard cornering. Lastly, most larger size tires these days only come in soft rubber compounds, so they wear quickly...having all four the same allows for rotation and thus longer tire life.
I dont think you'll need to go any lower in profile than 45 series...unless you try and go wider than 255,they you may need to drop down to 40s...good luck with your choices and remember to post up some pics when you get done...we love pics and interested to see your results.

Hey "ThunderBat"...I really don't Plan on going larger than 255, if I was to decide to Try it. But, what You are saying is, that if I try the 45 siries, it should Fit just Right? And, if that's all I need to Concentrate on...I Assume, I wouldn't have any sort of Significant Problems! And, I will Focus some Attention on the Off-set, Too...just in case, even though I am going with the 45 Series!

As for the "Rotation Issue", these will be used Only during the summer...of Course, so I wouldn't expect a Tremendous amount of wear, & I Definitely wouldn't be buying any Expensive tires, maybe some Nexen's or even Federal's 595...I live in the N.E. so Spring & Summer only last for a Short period...so, they maybe in use for approx. 8 mos. or so, if that Long. Then, I will go back to the Stock rims, 16's to Deal with the Snow.

The Only issue that may Worry Me...is the Issue of "Understeering/Plowing"...but, there is always a Remedy..."Remembering to Take it Easy around Hard Curves". And, if it happens to feels Terribly Uncomfortable, or Dangerous...I will then go down to 245's on all 4, for the next Summer.

But, for Now...it sounds Pretty Exciting to Me, but I Really Appreciate all You Help, & I will post some pics, when the GP it looking as I would Like it to LOOK! I guess, some Folks on the Road, that are aware of the Fact...that the GP is a FWD...will Think that I am Crazy, also!

But, I would be just Loving it...& "SlickGTP" No Offense, Ok? I was just a bit Confused there for a Min. but, I sort of Figured it was a Typo.

Thank You again, Guys...it's Great to have sort of a Family, to turn to for Advise.

heres a couple shots of mine with 18x9 38mm offset and 245/45/18 Rikens...I also have it lowered one inch and have had no rubbing or scraping issues...the ride is stiff mind you but just to give you an idea od what it looks like.

Dude, T-bat. Your car looks sick!

Tim, why you gotta make us mere mortals feel like garbage like that? That aint fair. as always, beautiful machine, man.

Cmon man, you're making the rest of us look bad

I can't remember.

Did I give you strong medication before you let me drive that, Tbat?

I am not worthy!

RD_GTP03: none taken...


Arcx: I think you slipped something into his drink at lunch. :p

T-Bat your car looks amasing. i was thinking thought. your car might look even sexier if you d-badged it. have you ever thought about doing this? i think it would look even better. not that it isnt now! looks awsome!

WOW!!! Hey "T-Bat"...that's an Awesome looking Machine, Maaan! You've got Me thinking of going Black...even Though, I don't think Mine will Ever look like That.

Did You Buy & Install...the Hood, it Sure give Your GP a MEAN Look, Great Job! But, if You don't Mind...with Lowering Springs, & base on Your Statement of Only Lowering it 1"...I sort of gather that One can Actually, set it at 1" or more? I sort of Imagined...that once installed...it would depend on the Springs, One chose.

I am Not considering going Lower at this Point...but, that's good to know...Who knows what I might Consider doing in the Future. It's Actually, the 1st Time...I have had a Ride, that sort of Inspires Me to Experiment, & Upgrade. And, You Guys here...do provide a World of Knowledge, & even if I do Express some Doubts, to Any of Your Suggestions...I Definitely, would give more credibility to You Guys that some Dealer, or the Mechanic around the Corner!

So, if I ever Question any of You Guys Opinions, or Suggestions...it's Not due to a Lack of Trust, Ok? Besides...You All, are Amazingly well Informed, possibly due to Lots of Trials, & Failures...& I Respect That!

I do agree, debadge that thing man!

Hey "TBat"...You've got My Respect! Your ride is Totally, "Kicking" Man...I Wish mine could look like That, I would "Never, Ever"...get rid of it.

But, I am Happy You posted those pics, it gives Me a pretty Good idea of what My wheels & tires will look like, when I install them. I just bought some "Motego's" 18x7.5...& I have been told that I can still fit some 245's on them, & if they are going to look like Yours...I will be as Happy, as a "Pig in S---".

In the pics...they appear to be 17" tires, but they fill-in the wheel well, Nicely...like if they belong There. For some reason, I was under the Impression that some "Low Profile Tires" would make that "4x4 look" appear even Worst. I
Guess, I just wasn't considering the Fact, that the wheels are 2" bigger.

However, they Truly look "Awesome" & let Your GP looks like it should be given...1st Prize at any "Auto Meet". But, have You had "Any Performance Issues" with the 18's?