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Help with stepping up to 17" wheels
#1
I've decided to step up to 17" wheels on my '71 fastback. I'm a little concerned about backspacing and hoping I can get some help from you folks. Here's the current situation:

Fronts: 15x7 Weld Draglites, 3.50" BS (WLD-90-57346)
Rears: 15x10 Weld Draglites, 5.50" BS (WLD-90-510350)

The rubber is a set of BFG Radial T/As in 235-60-15 up front and the rears are 295-50-15. The stance is great, car looks good, even handles good, but since I've upgraded the suspension quite a bit lately, I want larger brakes and better handling. I've decided on a set of 17" wheels based on size and backspacing as well: Centerline Nitro2s.

The rears are available in 17x9.5 with 5.50" BS. The fronts are available in 17x8 with BS between 3.50" and 5.50" in steps of 0.50" increments. What is going to be the best BS fitment and tire sizes for my '71 on 17s? I was thinking 285-40-17 for the rear and 235/245-40/45-17 up front.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged
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#2
You'll need shallow backspacing on the front. I tired to put the stock wheels from my 09 grand marquis on as rollers, and they wouldn't even bolt on. The rim was up against the upper control arm. They have the same backspace as the 05-14 mustang.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#3
Totalled;173210 Wrote:You'll need shallow backspacing on the front. I tired to put the stock wheels from my 09 grand marquis on as rollers, and they wouldn't even bolt on. The rim was up against the upper control arm. They have the same backspace as the 05-14 mustang.

What sort of backspacing would you consider shallow? Is 3.50" shallow? My 15x7 with 3.50" backspacing seem to be working pretty good right now. Not sure about 17s, though.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged
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#4
I think the SN197 wheels are like 5.5" so, probably.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#5
Well, I'm thinking of running 17x8 wheels with 4.0" BS, but I've read that as you add more BS to the front wheels, the handling goes to shit. So basically, I want to run the minimum amount of BS necessary to accomodate 245-45-17s. Will 17x8 with 4.0" BS contact any stock suspension components? My car is lowered 1".

The rear wheel is a whole different deal. I'm now considering running 17x11 with 6.5" BS to fit a 315-35-17 out back. From calculations it looks like it will fit my car.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged
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#6
My fronts are 17x8's with 4.25 backspacing and clear up front without any issues.

One problem with 17's in back is a limited selection of larger tire sizes. If you will ever have 400+ RWHP you will want a more flexible rim size such as 15's or 18's

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#7
Jeff73Mach1;173411 Wrote:My fronts are 17x8's with 4.25 backspacing and clear up front without any issues.

One problem with 17's in back is a limited selection of larger tire sizes. If you will ever have 400+ RWHP you will want a more flexible rim size such as 15's or 18's

I'm definitely going to be generating significantly more power than 400 RWHP. That's why I was thinking of running 335-35-17 on a set of 17x11s with 6.5" BS.

Thanks for the info on the 17x8s, I'll make sure I order greater than 4.0" BS then. Cheers! beer

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged
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#8
An interesting tire size, made only by 2 manufacturers that I see for street use. and very expensive.

Look at 18's for your rear and see what options it opens up

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#9
Jeff73Mach1;173423 Wrote:An interesting tire size, made only by 2 manufacturers that I see for street use. and very expensive.

Look at 18's for your rear and see what options it opens up

I don't think I was going for cheap in this case. Considering how much money I've put into my car at this point, a $250 tire is a drop in the bucket. Interestingly enough, Sumitomo offers tires in this size for about $150 each.

I did some investigation and it appears that there are several options for 315-35-17 tires:
  1. http://www.kumhousa.com/tire/category/ca...EA0466BD5C
  2. https://www.nittotire.com/Tire/Street/nt555#size
  3. https://www.nittotire.com/Tire/Street/nt05#size
  4. http://www.bfgoodrichtires.com/tire-sele...5/17/tires
  5. http://www.sumitomotire.com/assets/produ...ZSpecs.pdf
  6. http://www.goodyear.com/en-US/tires/eagl...6015400000

There's more, including Hoosiers and Toyos too, but I believe this is a kind of common sports car tire size. It looks like with a wheel with 6.5" BS they will fit with a good amount of clearance in and out.

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged
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#10
Mesozoic,

If you decide that you need spacers, here is one to look at.

http://www.mustangwheelspacers.com/index.aspx

mustang7173
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