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Evil Stu
03-18-2011, 08:23 AM
Hi guys,

First post here from a long time lurker.

I'm upgrading my 70 GTO from 15" to 17". Reading up I found that some say I can fit up to a 275/40/17 on a 9.5" wheel (5.5" BS) on the front and a 315/35/17 on an 11" wheel in the rear. Measuring I figured that was pretty tight on the back so I decided to be cautious and order ONLY the 9.5' wheels figuring iif my measuring was wrong I could always run 9.5" on the rear too. So I have the 9.5s here and I put them on the rear to have a good look before I order either 2 more the same or 2 17x11s.

Problem is I'm not sure still. Anybody here done this before can tell me what I'm looking at? I snapped a few pics and I'm hoping someone with more experience can tell me if I'm wrong in thinking that this is about as far as I should go.
Evil Stu
03-18-2011, 08:32 AM
Had to take some smaller, my straight edge there is exactly 3/4" thick and if I place it across the wheel face it is level with the inner lip. FWIW my axle is fairly well centered, out 1/8" side to side, driver's is the tight side.

Stu
PTS
03-18-2011, 09:57 AM
Had to take some smaller, my straight edge there is exactly 3/4" thick and if I place it across the wheel face it is level with the inner lip. FWIW my axle is fairly well centered, out 1/8" side to side, driver's is the tight side.

Stu

One thing to remember is that a 9.5" wheel is measured inside to inside bead. When measuring outside to outside you will have 10.5". Now a 2754017 on a 9.5 wheel is 11.00" sidewall to sidewall. Add a 1/4" to each side of the wheel on the outside and this will be approx the entire width of your package rear wheel and tire. Let me know if you understand or if I lost you.

Regards,

Perry
PTS
Evil Stu
03-18-2011, 02:59 PM
One thing to remember is that a 9.5" wheel is measured inside to inside bead. When measuring outside to outside you will have 10.5". Now a 2754017 on a 9.5 wheel is 11.00" sidewall to sidewall. Add a 1/4" to each side of the wheel on the outside and this will be approx the entire width of your package rear wheel and tire. Let me know if you understand or if I lost you.

Regards,

Perry
PTS

Perry,

Thanks for the reply. I follow, if I measure across the wheel lip to lip it is almost exactly 10.5". Can I use the same allowance of 0.25" each side for the 315 section tire on an 11" wheel? giving a total width of 12.5" (12" across the wheel + 0.25"x2), or do I need to allow more for the larger size?


Stu
PTS
03-18-2011, 03:38 PM
Perry,

Thanks for the reply. I follow, if I measure across the wheel lip to lip it is almost exactly 10.5". Can I use the same allowance of 0.25" each side for the 315 section tire on an 11" wheel? giving a total width of 12.5" (12" across the wheel + 0.25"x2), or do I need to allow more for the larger size?


Stu

Allow .75" on each side giving you a total tire width mounted on the 9.5" wheel of 12" approx.
opnwide
03-19-2011, 02:35 PM
I actually prefer the look of a 275 tire on a 9 or 8.5" rim and a 315 on a 10 or 10.5. The slight bulge looks more correct on an older car.
Evil Stu
03-19-2011, 04:01 PM
Allow .75" on each side giving you a total tire width mounted on the 9.5" wheel of 12" approx.


I actually prefer the look of a 275 tire on a 9 or 8.5" rim and a 315 on a 10 or 10.5. The slight bulge looks more correct on an older car.

I`ve only bought 2 wheels so far, I`m trying to decide whether to run the same 17x9.5 with 275/40 on all 4 or to go to a 17x11 on the back and a 315/35.

Unfortunately American racing doesn't make a 10 or 10.5, next size up from 9.5 is 11. Looks like I have room for an 11 with 6.25 BS.

Perry, your reply seems to imply that I can run the 315 on the 9.5 wheel, tire makers all seem to say 10" minimum for the tire.

Stu
cheapthrillz
03-19-2011, 04:14 PM
If it was me, I'd go with all the same size.... then you can rotate the tires if you plan on putting decent miles on the car...
JRouche
03-19-2011, 05:29 PM
I`ve only bought 2 wheels so far, I`m trying to decide whether to run the same 17x9.5 with 275/40 on all 4 or to go to a 17x11 on the back and a 315/35.

Unfortunately American racing doesn't make a 10 or 10.5, next size up from 9.5 is 11. Looks like I have room for an 11 with 6.25 BS.

Perry, your reply seems to imply that I can run the 315 on the 9.5 wheel, tire makers all seem to say 10" minimum for the tire.

Stu

Hey Stu, I think you have it right. Id go with the 11" and 315s on the rear. If they fit that is gonna be one killer look.

And I did a tremendous ammount of research when I was in the market for wheels and tires. I had massive ammounts of room in the rear. And I wanted 315 tires. YES, you can mount some skinny sumitomo 315s on a a 9.5" wheel. And those tires would look stretched on a 11" wheel. But, you cant mount some regular sized 315s (GY, BFG) on a 9.5" wheel.

Alot of the mustang guys will use sumi's on 9.5" wheels and they look good. I dont think Ive ever seen a GY or BFG 315 on a 9.5" wheel. Why? Prolly cause they dont fit right.

Not all 315 tires are the same. JR

GYs and Sumi 315s YES!! They are both 315 tires. Want some steam rollers with a nice "small" side wall, the GYs are pretty nice.
https://static1.pt-content.com/images/pt/2009/02/100_0053-1.jpg
Evil Stu
03-20-2011, 05:01 AM
JRouche,

Thanks for the pic, that is quite a difference. I knew that there were variations brand to brand but that is substantial. I was planning on BFGs or Contis. Maybe I'll go see my tire guy and order up 2 275/40 and have them mounted, then I'll be more sure.

Cheapthrillz, that is the best reason to have same all round. Car sees ~7500 miles a year, DD when it isn't snowing. I've been running different sizes front /rear for years and no matter how well aligned I keep it I can't make rear tires last..........
JRouche
03-20-2011, 05:58 PM
I settled on 10" wheels and 285/40 tires because I couldn't afford the next size up in the wheel that I wanted which were 12" wheels. Nuther 600 bucks a wheel. I really wanted 315 tires, but I could not swing the cost for 1200 wheels. 2400 bucks for two rear wheels didnt fit in my budget. Specially when I still have some other expenditures, like some real paint and an interior. Money is tight these days. JR

The 10" wheels and GY 285 tires. Not too bad, they hook up pretty well in the turns. My lil 350 will still cook them in the second gear swap from the 700-r4.

https://static1.pt-content.com/images/pt/2010/11/z-1.jpg

https://static1.pt-content.com/images/pt/2010/11/d-1.jpg
Evil Stu
03-22-2011, 04:46 AM
JRouche,

Are those GYs the Eagle F1 GS-D3?

Stu
johnnyksspeedshop
03-31-2011, 06:57 AM
Looks great with that set up!
FreedomRims
04-06-2011, 09:28 AM
Two suggestions, both of which I believe have been mentioned:

1) going with the same size will help the longevity of the tires as you can rotate all four, not just two, thus increasing life

2) go to your local tire shop and offer one of their guys a $20 bill to mount both sizes for you so you can have a looksy. prolly the best few bucks you'll spend.


Liz
Freedom Rims
Performance Tires (http://www.shopfreedomrims.com)