MonteCarloSS.com

Tire Size Help???

Posted By: iWON

Tire Size Help??? - 08/10/21 01:17 AM

1 inch lowering springs on 86 SS. Bought stock rims but 17’s. Was wondering what size tire to get, 4.25 backspacing. From measuring from ground to lip I come up with 215/55/17. That puts tires just below lip. Any help would be appreciated, don’t want to rely on tire shop, want a rough idea on what I should get.
Posted By: BadSS

Re: Tire Size Help??? - 08/13/21 03:56 AM

If your wheels are 8" wide with the 4.25" backspacing, most folks are running 245/45/17 or 255/45/17 on all four corners or 225/50/17 and 255/45/17s for a smaller/wider staggered look. I personally wouldn't run less than a 25.5" tire (any smaller looks funny to me) or more than 26.1" tire on the front with any kind of drop (could run into clearance issues). You can run a much taller tire on the back if you're going for a raked look.

Check out this link and click on 17" wheels to give you an idea of the different combination and sizes group by height.
https://tiresize.com/chart/
Posted By: iWON

Re: Tire Size Help??? - 08/13/21 04:42 PM

I saw user m202748 posted he had Nitto 555G2 245/45/17 on the front and Nitto 555G2 275/40/17 on the rear. Looked great in the pics just don't know if it will work on mine. I wish I could find a good enough tire shop that would know exactly what I need. Thanks for the link, I will definitely check it out...
Posted By: MAP

Re: Tire Size Help??? - 08/15/21 10:04 PM

Hi iWON,

How's your algebra? If passable, you can get all your answers, short of interference problems with the car's structure, from just two equations.

Best,
MAP
Posted By: 88ssBrent

Re: Tire Size Help??? - 08/16/21 12:32 AM

245/45/17 all the way around on 17x8 n90's. Can't remember exact amount of drop ill have too look back at my notes but I have coilovers all the way around and 2" drop spindles. I kept lowering the car all the way around until it hit going over a big dip near by then lifted a little on the coilovers. I did raise it a little in the front since the second picture, maybe a 1/2".

[Linked Image]

[Linked Image]
Posted By: iWON

Re: Tire Size Help??? - 08/16/21 03:05 PM

Thanks for all the replies, and nice looking ride 88ssBrent! I think I have the sizes down, just need to decide on if I want the staggered look, bigger in the back or same size all around. I know being able to rotate tires is a more cost efficient way to go. But it is not my everyday driver either...
Posted By: MAP

Re: Tire Size Help??? - 08/16/21 09:35 PM

Hi iWON,

It's hard to tell what your objective is. If it's looks, then the visuals will tell you all you need to know. My reaction to seeing any MCSS that's significantly lowered (like Brent's,) is that the shapes of the wheel wells no longer match the wheel centers. The correction is to raise the wheel well openings. In the picture above, I'm thinking a lift of 1" to 1.5" on the body would probably get that job done.

But again, it's all esthetics and what looks good to you.

If this is going beyond esthetics and you're concerned about handling, then that's another discussion.

Best,
MAP
Posted By: BadSS

Re: Tire Size Help??? - 08/20/21 11:09 PM

Originally Posted by iWON
I saw user m202748 posted he had Nitto 555G2 245/45/17 on the front and Nitto 555G2 275/40/17 on the rear. Looked great in the pics just don't know if it will work on mine. I wish I could find a good enough tire shop that would know exactly what I need. Thanks for the link, I will definitely check it out...


No problem on the link.

Be VERY mindful of the section width if you're going to try and squeeze a 275/40/17 on the 8" rim. Different manufacturer's section width run smaller (like Nitto) and large compared to the "norm". I personally wouldn't run that wide of a "daily driver" tire on the 8" rim. The smaller wheel pulls in the sidewalls and to get a flat foot print you have to run less air pressure in the tire. Doing so could effect handling and possibly over heat the tire. If you run recommended pressure, it will wear more in the middle and probably wouldn't have as much of a contact patch (rubber meeting the road) as SOME 255/45/17s (check the specs).

I wouldn't worry too much about running a 275/40/17 drag radial or true slick for the track (many do), because running less air pressure can be beneficial for straight-line traction - well hopefully you're only going straight!
Posted By: MAP

Re: Tire Size Help??? - 08/21/21 09:20 PM

According to the equation I've posted in the sticky, 275/40 belongs on a rim that's 9.5" wide. If handling is very important, then 10" or even 10.5" wouldn't be out of the question.

Putting that tire on an 8" rim would be a big mismatch; I agree with BadSS!
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