Any '67-68 Gen F-bodies w/ 285/40s?

[68Formula]

I have 275/40R17s on right now with a 9.5" rim and 5.5" backspacing. Looks like if I roll the lip, I might be able to go up to a 285. The rear is stock height (springs fairly stiff) and I have no plans to lower it.



Is anyone else running this size on a '67-'68 with my rim dimensions? Any rubbing?

[sporter]

This guy runs 285s on his 68 Firebird.





Article on Firebird with 285/40-17s

[68Formula]

Sporter, doesn't matter which site I'm on, you're always there to help!

Wish they said what the backspacing was. From the dead-on shot, they look like they may be flush with the lip. But he does have a 1/2" narrower rim, which would affect the effective width slightly.

Wish I had gone with 17x10s with a 6" backspace.

[Woody]

Did you see Streetfytr68's thread "How not to fit 18 x 10". Plug in 285 in the search feature and it is the second thread that shows up. I know this is for an 18", but maybe some of the info will help.

[tripower]

Wish they said what the backspacing was. From the dead-on shot, they look like they may be flush with the lip. But he does have a 1/2" narrower rim, which would affect the effective width slightly.

Wish I had gone with 17x10s with a 6" backspace.

I have the original mag with that car at home. In the original article there's a side bar where I think he discusses the BS and mentioned that he might be able to go with a larger tire. I'll see if I can dig it up and post the info on Friday. Shoot me an e-mail if i forget to post.

[68Formula]

I have the original mag with that car at home. In the original article there's a side bar where I think he discusses the BS and mentioned that he might be able to go with a larger tire. I'll see if I can dig it up and post the info on Friday. Shoot me an e-mail if i forget to post.

Thanks, look forward to it!

[tripower]

Here's what was in the article:

front - 17x8 6" BS 225/45-17
rear - 17x9 7" BS (should have been 6.5" BS) 285/40-17

He stated that the fronts were running 6" BS and the rears were 7". He further states that the rears should have been 6.5" BS as he's running a .5" spacer. He reports no rubbing in the rears and that 315 tires "might" be possible. On the front BS, one tire hit the upper a-arm on hard turns. This was solved by clearancing the arm.

Hope this helps!

[68Formula]

If he can fit 315 tires, he's mini-tubbed it.

Mine show a hint of rubbing during hard cornering. (Witness marks on the undercoating). And my suspension is completely new. I would think also, that the 1/2" decrease in width would increase the tire buldge. And that the effective backspacing would be deeper than mine.

Thanks for checking that out though.

[tripower]

If he can fit 315 tires, he's mini-tubbed it.

He only said he "might" be able to fit them. The article didn't say anything about mini-tubbing, but at the strip he was only running 275/50-15 drag radials. I bet he's speculating on the 315's and that his wells are stock.

The BS on the fronts seem rather deep.

[68Formula]

True, I could probably fit them if I only drove in a straight line. I think sometimes people forget about the flex when going into corners.

The BS on the front is too deep. Probably why is only running 225s.