How wide can I go on a 77 Firebird?

[Project77]

I'm looking to upgrade my wheels and tires next. Should I go 18x9 on all four corners or put 18x8 in the front? I've seen a late 2nd gen Trans Am online with 18x9's all with 275/40/18 Nitto 555 tires and it looked good in the pics... but I worry about a tire that wide fitting up front. Any advice? Here's a pic of US Mags Bandit wheels I plan on running:

86348

[Henesian]

As a reference, Year one has their 17x9 reproduction snowflakes that are designed to fit on a 2nd gen bird with 275/40/17s all around and no rub. To do this, they use 4-7/8" backspacing. I'm running this setup, and I have no rubbing issues, even on hard cornering with leafs in the back. It helps to roll the front fenderwells and your backspacing has to be spot on. Also helps to have a bit of negative camber. Also, a 275/40/17 = a 275/35/18, which is a tad wider/equal width than 275/40/18 with less height. On third thought, I think it would be harder to get a 275/40/18 under the front because of the tire height. Hopefully someone else can add some more information.

[Project77]

In the pic below he has Year One 18x9 Snowflakes with 5.25 backspacing like the 18x9 US Mag Bandits. The wheels and tires I have now are 27" and the Nitto 555 275/40/18 are 26.61".

86368

[Henesian]

It doesn't seem like he does anything extraneous to make it fit. By how the tire looks in the wheelwell, it looks like he's running the stock front suspension. You should be pretty good then.
https://static1.pt-content.com/images/pt/2013/09/TA-1.jpg (http://smg.photobucket.com/user/Zaxium/media/TA.jpg.html)
Here's my 76 T/A with the 275/40/17s on 4-7/8" BS 17x9 YO snowflakes. I can say from experience that with the stock 1.25" front sway bar, I lose a couple degrees of steering way at the end, but it doesn't feel dragged down in the front, because I have the super fast steering box from 76. I would pull the trigger, man. Big as you can go in the front is better.

[Project77]

That's one nice looking '76!!!

[Henesian]

That's one nice looking '76!!!Thanks. I think you should go with the 275/40/18 setup all around. The handling will be pretty awesome. It definitely pays to get as much meat up front of the car as you can. Also, if you end up going 295s or 315s in the back some day, you'll have a large enough tire in the front that it wont add any noticeable understeer. And it'll just look extremely badass, which is always an added bonus.

[opnwide]

275s rubbed too much on my car when I had it slammed. Now I'm only lowered about 2", and rubbing only at full lock and big bumps. Kumho doesn't make a 265 in their XS, and I think 255 is a little too small for me. So stick with the 275, and just be careful. This is about 3.5" lower than stock (too low!)
https://static1.pt-content.com/images/pt/2012/07/screensaver17s-1.jpg

[Project77]

Thanks for the info Greg. I've talked to more people and I'm going with 275's in the back and 245's up front. It looks good and won't rub up front for sure. I just put the last piece of my Hotchkis TVS stage 2 kit on today. My ride is pretty low. If there's any rubbing I can raise it an inch no problem.

[krwyellowz28]

I had the 17x9 YO Snowflakes on my '79 with 245/45/17's up front and 285/40/17's out back. The rear fit with some minor BFH massaging and really looked good. If I were do it over again I would go with 255/45/17's up front to match the 9" rim a little better.

https://static1.pt-content.com/images/pt/2013/12/20120508_200318_638-1.jpg

https://static1.pt-content.com/images/pt/2013/12/20120508_200004_629-1.jpg

https://static1.pt-content.com/images/pt/2013/12/20120508_200111_694-1.jpg

[72blackbird]

Brian,
Now that you already have your wheels, you know that you're locked into a max width- with 18 x 9s the widest you can go is a 275 section width tire. To go 285's you'd need a 9 1/2" wide rim, and to go 295 you would need a 10" wide rim- these are the manufacturer's minimum rim width, but these sizes can run on even wider rims. These widths obviously push the practical limits especially in front, but if you do a bit of research you find some guys will even run a 10" wide rim on the track.

The widest tire I've seen anyone run up front is a 285/35R18- if you've seen this tire in person it's pretty wide. The only way I could see fitting it is to get it on the car and lower the ride height slowly, taking the car through a section of twisty roads before dropping it another increment to make sure it doesn't rub.

Geno