Hi everybody! I need one or two pirctures of 3rd Gen Trans Am or Firebird with 8.5x18 wheels and 275/35 R18 tires mounted in the back, to prove that they will fit my car. I've already searched here and at google but I couldn't find something...sorry. Thanks in advance, Mario PS: If you're wondering why I don't just mount them ... I'm from Germany and our laws regarding cars are so

Dunno about 18x8.5, but here is 275/35/18 on a 18x9.5:

I have 18x9.5's in the basement with 275/40R18 tires on them. Went to bolt them up the other day and I discovered I had to beat the hell out of the inner fender. Its really not that hard to do though, it was only in one small spot that it rubbed. I guess we'll see how it does once I drop the car a little bit though

Haven't put them back on yet, waiting for warmer weather. Just figured I'd get all the fitment issues out of the way while I was working on some other stuff back there.

Hey hawaiian,what size offset you got?

Ah, just for reference, I'm using C5 vette wheels on a 4th gen rear and no spacers.

I think what mk_private is wanting to know is if the tread goes outside of the wheelwell. I believe in Europe the tread of the tire cannot go outside of the cars fender (but the wheel can - retarded).

I have C5 wheels (18x9 or 18x10, I forget) on a 3rd gen rear with 2" spacers; they are easily inside the fenders. Their 17" mates on the front also with 2" spacers.

My wheel is 18x9.5 w/ 5.5" backspacing. Didnt specify any offset, in fact Boyd told me they dont go by offset anymore. I guess you could custom order some specific offset if you wanted. Thats the cool thing about Boyd, you can custom order every aspect of the wheel.

CrazyHawaiian if you do not mind me asking how much were your wheels. I ordered some ROH Comp Drift R's from Group A and it is taking forever. It has been two months and counting with no end in sight. If boyd could cut me some wheels that would be cool.

CrazyHawaiian,

With 5.5in backspacing, how close is the tire to the inside of the wheel well? I've been looking at BC Forged wheels (Boyd's son) and they will customize the offset too. I want the 275's like you have and I want to make sure I get the best fit possible.
Thanks.

Hi guys!
Thanks for your postings...

Here in Germany the laws are so ridiculous ... we need a inspection after changing any part of the vehicle...and especially american cars are a problem, because the most cops here think that the drivers of those cars are pimps, criminals or insane and that's why they confiscate cars even for changing parts like the hood, a rear wing etc.
Running a non factory rim and/or tire will result 3 points for each wheel (=12 point saved for years in a list) and with 18 points in this list you are losing your driver's license !

This are some of the reasons why I need as much information as possible to get the rims & tires I want legalized by a licensed engineer.

I want to use a 8.5 x 18 wheel with a 0 offset and 4,75 backspace with those 275/35 18 wheel in the back. Regarding your postings they should fit whithout going outside of the fender ... am I correct ?

Will this rim (8.5 x 18 4.75 backspace) also fit in the front without using spacers ? I want to use 245/40 18 tires on it !

Thanks,

Mario

I know what you mean about the rules, I lived in GE for two years and the locals had the same issues. It sucks!

A 245 tire on an 8in wheel will fit Ok, it will just rub a little bit on the inside if you turn the wheel all the way. You can fix the rub by changing the turn stop on the steering (keep it from turning as far). I've been looking to run 275's on the rear like you, and they will fit but it will stick out a little bit. If you do some searching on this board you can find one or two pics from the back of the car. Maybe PM Crazy Hawaiian and ask him to post a pic from the back of the car.
Good luck with the cops over there.

mk_private, I am running the same tires sizes you want to run but wider wheels. 245/40/18 front on a 18x8 with 4.5" backspacing, and 275/35/18 rear on a 18x9.5 with 5.5" backspacing. With the Eibach Sportlines (advertised 1.*" drop), the car had no issues with rubbing in the front or rear, even at full lock turning. I did not modify any parts of either the front or rear wheelwell for them to fit, the rear lip isn't even rolled. Everyone I asked locally told me it wasnt possible, but they were all wrong. I knew they would work because I copied the backspacing and tire widths of known good setups here in TGO, just applied to a different size wheel.

mk_private, I''m fairly certain 18x8.5's with 4.75" backspacing will fir and require no modification to either the front or rear wheelwells. In fact, you could even go wider and still not require modifications. A good way to research the issue of wheel widths and what backspacing/offsets will work is to do searches using more common wheel diameter sizes, and the widths you want to use. For example, if you wanted to run 18x11 in the rear, I would do a search on "17x11" and see what guys running 17x11's had to do to get the wheels to fit. Then when you apply that to your 18's, the only change would be the sidewall of the tires, and maybe the tire widths. The key to this is making sure the end result overall wheel dimensions are close to stock. Using a wheel calculator, you can safely determine what larger size wheel specs will fit, as long as the overall dimensions are close to stock (example, 254/40/18 and 245/55/16 are very close overall dimensions) and you use known good width/backspacing combos. Thats how I knew a 18x8 with the same backspacing as stock would fit perfectly with a 245/40/18 tire, and it did. Thats also how I knew the rears at 9.5" wide with a 5.5" backspacing and 275/35/18 tire would fit (guys with 17x9.5 and 275/40/17's had no issues).

A10Beav, here are some shots showing how the rear wheels sit in relation to the fender:

Thanks for the info and pics!

Unfortunatly for me I asked to get the star removed from the center of my hotrods and was told that boyd wont 'change' their designs for any reason....period. Meh I guess

@CrazyHawaiian
Thank you so much for the pics and the detailed explanations. I guess with all that information the engineer has to give his OK and you made it all much easier for me. I guess now I also do understand all this confusing stuff about rims & tires. Thanks again.

@A10Beav
Thanks to you too. It is good to "hear" that you know the problems we have here...for someone who wasn't here before it must sound like we're all crazy over here... I guess the 2 years here in Germany must have been a horrible time for you wasn't it !? Have you ever been in Grafenwoehr (Camp Chep) or Vilseck (Rose baracks) ? That's only 30 miles away from me...just to let you know in what boring area I'm living...

Thanks again,
Mario

Actually, I had a great time in GE; aside from the constant cloudy weather The rules you guys have to put up with don't apply to us because we're not GE citizens. I bought my Firehawk while I was in GE and drove it for my last year there, it was blast! I had a great time driving around most of GE and other parts of Europe, I'd go over there again if I had the chance

BTW - I was in the Bitburg area. Great spot to travel from, I could drive almost anywhere in 6 hours or less.