Going from 15's to 17's, question about backspacing for the rears.

[torino420]

My car has 15x8's with 4.5" backspacing with 295 50's. The wheels are damn near centered in the wheelwell.
I know theres that cool tool for determining proper backspacing but I'm looking for opinions since the 8's fit perfectly.
When I measure from both the inner and outer edge of the wheel i have about 1.5" minimum clearance. With that in mind what backspacing do you think i need to run a 17x9.5" wheel.
I have to custom order the rears so they need to be right.
I have an idea what backspacing i need but want some other opinions.


thanks

 

[dodgestang]

5.25 will put the center of the 17x9.5 in the same place as the center of the 15x8 4.5bs

 

[thekid760]

will that fit on the stock rear of a 65 mustang GT? what about tire size?

 

[Pakrat]

What size tire are you planning on? I just custom ordered some 17x9.5 rims a while back for the rear of my 69' and I plan to run a 275/40/17 on them so I went with 5.5" BS.

 

[torino420]

285 40's...

 

[dodgestang]

will that fit on the stock rear of a 65 mustang GT? what about tire size?

No. Once you mount a tire it will be too wide for the stock wheel wells IMO.

 

[65fastbackresto]

I can tell ya something NOT TO DO

Some bozo stuck 17 by 9.5 on my 65, 4 1/2 inch backspacing, and they rub when I hit a bump with 3 or more people in the car. I do think 5 inch backspacing would fix it though.

 

[Pakrat]

Geez, they must stick out way past the fender too.

 

[65fastbackresto]

No they dont stick out at all

Its all tucked under the fender, but a little to close to the upper inside well. It just BARELY rubs when I hit a bump. With a shorter tire, it would prob fix it, but a shorter tire would never fix the front.

 

[Pakrat]

Hunh, I'm having a hard time visualizing how it could be tucked at 4.5 BS when that's what you would use on an 8" rim?!??!! That extra 1.5" has to go somewhere.

 

[ron67fb]

I have yet to see pics of your car, 65fastbackresto. So far I've gathered you have 10 and 9.5 inch wheels, 4.5-inch backspacing, 215/45-17s... ??