About to order rims & tires, want to double-check.
 

Finally going to bite the bullet and order the Intro Vistas I've been craving for years. These will be going on the '65 GTO in my signature. I've read just about every thread there is (here and elsewhere) on sizing and fitment and I just want to double-check before ordering. The car is about as low as northeastern roads will allow, and I've tried to take that into consideration.

I'm planning on being relatively conservative: 17x7s up from, 4.5" backspacing, and 18x8 in the rear, 5" backspacing. That's with Baers, and thus an additional .25" of track width per side. Sound okay?

For tires, I really wanted the BFG g-force sports, but they don't seem to have the profiles/height that I need. The Goodyear F1 Gs-D3s have all the combos I am considering, so I am planning on going with those in custom redlines.

Right now, I'm leaning towards a 235/50/17 (26.3") front and 255/45/18 (27.1") rear tire. I'm currently running 26" tall tires that are about perfect, but with larger rims I wanted a little extra sidewall just to be safe. Thoughts?

Sounds good, I highly recommend the GS-D3s for a street driven car. They are great in the rain and even better dry.

Thanks for the reply - I was beginning to think that no one cared. :D

With a large car like yours I'd consider moving that rear tire up one more size to the 275/45/18 (if you can make the width work in your wheel well) might be a better match of scale and would give just a little extra rake.

I agree. When we did Bill's GTO we mocked it up with 335 / 18s and they looked like donuts in the huge wheel wells. I would look for a taller tire.

I'd love to go up a size, but I don't think I'm going to get anything bigger than a 255 in there without a minitub or at least some major work with a 5lb sledge. I know of a few people who have run a 275 in a '64-65, but I don't think it's something I want to try to tackle. I'm trying to stay slightly conservative with a 7" wheel up front and whatnot.

I guess I could stick with a 255 and go to a 50 series tire?

Scratch that last idea, basically no tires in that size.

Just for reference, here's the car with its current 215/65/15s (26") and I think they look tall enough. And I'd be going an inch higher with the 255/45/18.

Edit: Damn, pics won't fit. Will resize and try again tomorrow.

Yeah, but you're doing it at the expense of about 25mm of sidewall:
255/45=114.75mm sidewall
215/65=139.75mm sidewall
Thats really going to be a huge contrast, additionally your front tire while smaller in diameter, will have more sidewall, and likely look out of scale
235/50=117.5mm
If you can make the 275/45 work you'll have 123.75mm sidewall which will scale well with your front and give you the height you want.
Those wheel wells aren't anything a six pack and a bad attitude can't take care of:thumbsup:
My numbers above are just the straight math, every tire mfr varies a bit so take it for what it's worth (some tell me not much...)

I'll do some math and measuring on the 275s.

But as long as I am running a larger wheel in the rear, I'm going to be looking at less sidewall, right? Unless I make it up in tire height, which probably means going wider to stay with the tire I want (F1 GS-D3).

No wonder it's taken me so long to order.

How about a 225/50/17 (25.9" tall) front and the 255/45/18 (27.1" tall) rear? That would be a 4.4" front sidewall and a 4.5" rear. Sound better?

Finding tire sizes that work for you, and a tire mfr/model that cover both front and rear sizes is truely a PITA.
The sizes you mention above would work well together, same size sidewall and slightly larger diameter rear. A-Bodies are deceivingly large cars, 27" rear is as small as I would go. My last car was a Buick GS400, I ran a 28"+ 275/55/17 tire on the rear (after installing a smaller tire and not liking it) and it was perfect.
In the end you may have to go to a shop and have a couple different sizes installed and see just what makes you happy.