Biggest front tire size?

[06 T-RED S/C GT]

Roush wheels are 10" wide with 45mm offset. But that's a moot point, and the steering stops are required on their 20" wheels..required so the wheels don't smack the inner wheel wells. A 9.5" wheel would require no where near 45mm et. A 9" wheel only requires a 30mm et.

WRONG !!! And I strongly suggest you look at the Roush website.. In fact they don't even list 20x10 wheels anywhere on the site under 2005-15 Mustang parts..

All wheels for 2005-2015 Mustang are listed as 20x9.5 and require the steering stops on their 20" wheels... In addition, I recently purchased a set of Steeda Spyder 20x9.5 wheels which are also 45mm offset..

As for 9" wheels only requiring 30mm offset, wrong again.. As not all have just 30mm offsets.. FYI I was also considering the Mickey Thompson SC-5 20x9 wheel which have 32mm offset and also Niche Verona Anthracite 20X9 wheel with 35mm offset..

Posted below are links from Roush, CJ Pony Parts and LMR that list the offset for the Roush 20x9.5 wheels at 45mm.. And btw: the Roush wheels were also one my choices as well in which the Roush tech I spoke with also confirmed the offset is 45mm along with the 20x9.5 wheel size..

In the end, I decided against the Roush wheel package after the tech rep I spoke with confirmed the steering rack stop kit is definitely required..

Prior to purchasing the Steeda Spyders, I did have doubts about clearance with the 45mm offset, however after the tech rep I spoke with assured me about the Spyders being engineered specifically for the S197 Mustang and are designed to fit properly in addition to also being included on their Steeda Q series models, I finally made the decision to place my order and received them 7 days later..

With that being said ! Here's the links including specs..


http://www.roushperformance.com/parts/ROUSH-Mustang-20-inch-Graphite-Wheel.html


https://lmr.com/item/RSH-420034-K/Roush-Mustang-Wheel-Kit-20x95-Chrome-05-14

http://www.cjponyparts.com/roush-wheel-20-x9-5in-hyper-black-2005-2014/p/W111-V/

http://www.cjponyparts.com/roush-wheel-20-x9-5-graphite-five-spoke-2005-2014/p/W527-V/

http://www.americanmuscle.com/niche-anthracite-verona-20x9-0514.html

http://www.americanmuscle.com/silver-mt-sc5-20x9-0514.html

 

[mavisky]

20x10" at all 4 corners, +48mm offset, no steering stops, no rubbing.

 

[Norm Peterson]

Roush wheels are 10" wide with 45mm offset. But that's a moot point, and the steering stops are required on their 20" wheels..required so the wheels don't smack the inner wheel wells. A 9.5" wheel would require no where near 45mm et. A 9" wheel only requires a 30mm et.

Going 15mm lower than Ford's own 9.5" wide wheels is likely to bring on negative consequences, including instability under hard braking from speed.

I know the hard-parkers and the hella-flush appearance folks aren't likely to encounter that, but then again this discussion isn't about their wheel questions.


Norm

 

[06 T-RED S/C GT]

Ford's 18x9.5 SVT wheel have a 45mm offset with 7.125 inches of backspacing..

My Steeda Spyders are 20x9.5" with 45mm offset with 6.9 inches of backspacing.. Roush wheels are 20x9.5 with 45mm offset.. They are NOT 20x10"..

Gabe's Niche Milan wheels are 20x10" with 40mm offset in which he hasn't experienced any clearance nor negative consequences whatsoever and runs them as a square setup both front and rear..

So just how in the hell do you figure the Roush wheels along with my Steeda Spyders are considered 15mm lower than Ford's own 9.5" wide wheels when they are both within the same backspacing and offset measurements..

Therefore according to your logic where do you come to the conclusion that the Roush wheels will likely bring on negative consequences, including instability under hard braking from speed, when they were designed and engineered specifically for the S197 Mustang ?

At any rate, I respectfully disagree with your logic, as your numbers just don't add up at all..

https://lmr.com/item/M1007S1895/2007-11-Mustang-Machined-Gt500-Wheel-18X95-M-1007-S1895

https://performanceparts.ford.com/part/M-1007-S1895

http://www.steeda.com/steeda-black-spyder-wheel-20x9-5-013-0021-45b/

 

[Norm Peterson]

So just how in the hell do you figure the Roush wheels along with my Steeda Spyders are considered 15mm lower than Ford's own 9.5" wide wheels when they are both within the same backspacing and offset measurements..

The +30 offset was Pentalab's number for his "minimum-offset" fitment. I never expected my directly quoting him would ever allow either my math or conclusions to be misinterpreted all the way out to your +45 offset wheels.

Therefore according to your logic where do you come to the conclusion that the Roush wheels will likely bring on negative consequences, including instability under hard braking from speed, when they were designed and engineered specifically for the S197 Mustang ?

I was never talking about the Roush wheels. Only the +30 offset, with math and conclusions applying only to those wheels that use +30 (+32 offset wheels would be different, but only slightly so).

I have a set of the 18" SVT/FRPP/GT500 wheels in exactly the specs you've presented, which is fine.

However, I am curious as to how your Steedas with the same claimed width and offset as my SVTs end up with only 6.9" backspacing. That tells me that the Steedas either have a pretty thin inside flange or their width is being measured a little differently. Or maybe a little of each. Granted, the SVT wheel's flange is likely to be a little thicker than most given its OE-level use. But almost 1/4" difference on the inside flange (0.225") is huge when wheel flanges are only about half an inch thick. Even half of that 0.225" difference, let's say 1/8", is still significant in terms of strength.


Norm

 

[Tungsten_GT]

You sure about it being positive?


My experience - you'll probably rub the strut unless you're running something like Cortex's struts that provide extra wheel and tire clearance. Or run a thin spacer with the FRPP hubs (it's getting the ARP studs that really matters here).

My track tires are only 285/35's, but they're mounted on 11" wide wheels which brings their actual as-mounted section width out very close to 295mm. I have 1.2mm strut clearance at both the tire and the wheel, and it took a very thin spacer (0.025") to get that much on one side even though the other side measured the same clearance without any spacing. Things like actual strut diameter and offset to the strut/knuckle mounting holes are critical unless you're willing to let more than just the tire sidewall and the outer flange of the wheel peek out past the sheetmetal. My car has been lowered half an inch since these pictures were taken, which would make the relation between the tire and the sheetmetal a little more distinct, but I haven't taken that picture yet.


On edit, at the very least plan on running more strut-side clearance because a 295/35 on 10" is going to flex more than a 285/35 on 11".


Norm

Negative, whoops, and I might test fit a tire to see, the SVE drifts do have a similar offset compared to the Roush wheels I believe, they are a +43mm

 

[06 T-RED S/C GT]

The +30 offset was Pentalab's number for his "minimum-offset" fitment. I never expected my directly quoting him would ever allow either my math or conclusions to be misinterpreted all the way out to your +45 offset wheels.


I was never talking about the Roush wheels. Only the +30 offset, with math and conclusions applying only to those wheels that use +30 (+32 offset wheels would be different, but only slightly so).

I have a set of the 18" SVT/FRPP/GT500 wheels in exactly the specs you've presented, which is fine.

However, I am curious as to how your Steedas with the same claimed width and offset as my SVTs end up with only 6.9" backspacing. That tells me that the Steedas either have a pretty thin inside flange or their width is being measured a little differently. Or maybe a little of each. Granted, the SVT wheel's flange is likely to be a little thicker than most given its OE-level use. But almost 1/4" difference on the inside flange (0.225") is huge when wheel flanges are only about half an inch thick. Even half of that 0.225" difference, let's say 1/8", is still significant in terms of strength.


Norm

Norm ! After I read your post, I contacted Rod from Steeda to inform him I was concerned about the 45mm offset causing a possible clearance issue being too close to both the strut and sway bar links.. When I asked if it might be necessary to purchase the steering rack stop kit, his response was that he would sell me a kit, if it would resolve any doubts I have concerning clearance issues..

However he also stated that out of 99% of customers that have purchased the Steeda Spyder wheels, there have been no reported claims of any clearance or rubbing issues at all..

I also asked Gabe to ask a buddy of his who also runs the Steeda wheels on his 13 GT, if he's noticed any clearance problems and claims he has plenty of clearance space using 275-35-20" Nitto 555 G2's with the Spyder's and in his opinion he could also run 285-30-20's if he wanted and still be able to clear..

Anyway I still haven't got around to installing the Steeda's just yet, but as soon as I get a chance to test fit them, I'll be sure to post the results either way and if in the event they don't clear ? I will return them, that you can be assured of..



-Rocky

 

[Norm Peterson]

If anything, and that 6.9" backspace is correct and measured exactly the same way the 7.12" was for the FRPP/SVT wheels, you've got more wheel to strut clearance than either I have or what the 2008-ish GT500's had (I had a bit more than 3/8" with 255/45-18's, which is way more than "plenty"). You gain a little wheel clearance with 20's vs 18's because the strut slopes away from the wheel as you go up. You don't gain as much clearance at the tire as you do at the wheel because the widest point on the tire doesn't move up by the same amount when you hold the tire OD constant.

Chances are that even with 285/30's it'd take a pretty serious combination of tight turning and bump-hitting to cause a tire rub, but there are people who are really sensitive about that sort of thing.


Norm

 

[oldVOR]

Each Mustang is a little different, therefore, the fit of a particular wheel will be different. When I test fit 18x9.5 et45 SVT/FRPP/'07 GT500 wheels on my sons '05 Base model, full lock to lock had hard contact wheel inner lip to LCA at the back-side leg, both left and right sides. Clearance on the front-side and swaybar was plenty. Clearance to the strut was plenty. SVT/FRPP states steering stop 6R3Z-3932-CA is required. Steering stops were installed (rather easily) and this afforded clearance between the wheel inner lip and LCA.

 

[06 T-RED S/C GT]

If anything, and that 6.9" backspace is correct and measured exactly the same way the 7.12" was for the FRPP/SVT wheels, you've got more wheel to strut clearance than either I have or what the 2008-ish GT500's had (I had a bit more than 3/8" with 255/45-18's, which is way more than "plenty"). You gain a little wheel clearance with 20's vs 18's because the strut slopes away from the wheel as you go up. You don't gain as much clearance at the tire as you do at the wheel because the widest point on the tire doesn't move up by the same amount when you hold the tire OD constant.

Chances are that even with 285/30's it'd take a pretty serious combination of tight turning and bump-hitting to cause a tire rub, but there are people who are really sensitive about that sort of thing.


Norm

I've went ahead and posted the e-mail sent from the Steeda rep about how he calculated the backspacing measurements for the 20x9.5 Spyder wheels..

Perhaps you can confirm if his calculations are either accurate or not accurate Norm..


-Rocky
---------------------------------------------------------------------------------------

Steeda wheels

5/9/2016
Hi Rocky,
I do not have one to measure here.
You can do the math and get close.
Here is how it works.
first, backspacing is the distance from the rear edge of the wheel, INCLUDING THE WHEEL LIP, to the face that bolts on to the brake rotor.
So to measure it, you lay a straight edge across the wheel lip and measure from it to the face that attaches to the rotor.

To calculate it using math, you take the wheel width and convert it to metric.
So we take 9.5 and multiply it by 25.4
That is 241.3
So if the wheel had ‘zero offset’, it would mean that we would have to take 241.3 and divide it by 2
That is 120.65
but our wheel is a 45mm offset, so we add that to the 120.65 giving us 165.65 as the distance from the inside edge of the wheel to the face that bolts on to the rotor.
To convert that to inches, divided it by 25.4, so that gives us 6.521 inches.
But this is not the backspacing, since backspacing includes the lip.
In general, the lip adds about 3/8 of a inch to the 6.521 calculation
So it will be around 6.8 to 6.9
Hope that helps.

Rodney Williamson
Sales & Support
Direct Phone: 954-718-6512
[email protected]

 

[06 T-RED S/C GT]

Each Mustang is a little different, therefore, the fit of a particular wheel will be different. When I test fit 18x9.5 et45 SVT/FRPP/'07 GT500 wheels on my sons '05 Base model, full lock to lock had hard contact wheel inner lip to LCA at the back-side leg, both left and right sides. Clearance on the front-side and swaybar was plenty. Clearance to the strut was plenty. SVT/FRPP states steering stop 6R3Z-3932-CA is required. Steering stops were installed (rather easily) and this afforded clearance between the wheel inner lip and LCA.

So in other words, the 20x9.5 wheel may end up hitting the inner wheel well lip and back side leg of the LCA ?

 

[Norm Peterson]

I've went ahead and posted the e-mail sent from the Steeda rep about how he calculated the backspacing measurements for the 20x9.5 Spyder wheels..

Perhaps you can confirm if his calculations are either accurate or not accurate Norm..


-Rocky

Thanks, and I can follow his logic just fine. Where I differ is that flanges, including any lip, are apt to be closer to 1/2" thick, so 3/8" sounds a little "light" to me.

The actual width of a wheel might be a little fuzzy, as its measurement at the bead seat is not between sharply defined points, but to some sort of radius that's specified by the contour designation (letters like "J" or "JK").

The SVT wheel's inside flange is a little more than 1/2" (7.12" backspace on a 9.5" wide wheel with +45 offset calculates out to 0.60" approximately).


Norm

 

[06 T-RED S/C GT]

Thanks, and I can follow his logic just fine. Where I differ is that flanges, including any lip, are apt to be closer to 1/2" thick, so 3/8" sounds a little "light" to me.

The actual width of a wheel might be a little fuzzy, as its measurement at the bead seat is not between sharply defined points, but to some sort of radius that's specified by the contour designation (letters like "J" or "JK").

The SVT wheel's inside flange is a little more than 1/2" (7.12" backspace on a 9.5" wide wheel with +45 offset calculates out to 0.60" approximately).


Norm

So let's say in the worst case scenario the inside flange is closer to 1/2" (7.125" backspace rather than the 3/8" (6.9" backspace as Steeda claims.. With running a 275-35-20 tire on their 20x9.5 45mm offset, in your opinion should I be concerned about possible clearance issues ?

Here's more specs I located from the backside of the wheel..

ND S181 20x9.5 JJ
ET (45) H
DOT- J

Hopefully this may provide more detail concerning the flange dimensions ?

 

[Norm Peterson]

Not regarding clearance to the strut anyway.

I've never thought to check down at the LCA to see whether a 20 of the same backspacing as an 18 would run closer or hit it sooner.


Norm

 

[06 T-RED S/C GT]

20x10" at all 4 corners, +48mm offset, no steering stops, no rubbing.

Do you happen to know what your backspace inches are by any chance.. Also what brand are your 20x10's ?

 

[oldVOR]

Thanks, and I can follow his logic just fine. Where I differ is that flanges, including any lip, are apt to be closer to 1/2" thick, so 3/8" sounds a little "light" to me.

The actual width of a wheel might be a little fuzzy, as its measurement at the bead seat is not between sharply defined points, but to some sort of radius that's specified by the contour designation (letters like "J" or "JK").

The SVT wheel's inside flange is a little more than 1/2" (7.12" backspace on a 9.5" wide wheel with +45 offset calculates out to 0.60" approximately).


Norm

Norm,

3/8" sounds normal for old-school steel wheels.
Most modern alloy wheels are closer to 5/8"

 

[oldVOR]

So in other words, the 20x9.5 wheel may end up hitting the inner wheel well lip and back side leg of the LCA ?

The LCA curves toward the rear mount and there may be more of a clearance issue with 20" wheels. Alot depends on the build of the car. '05-10 base V6's have no steering stops, '05-10 GT's have the thinner steering stop and '07-10 GT500's have the thicker steering stop.

I'll measure my son's '05 with the SVT/FRPP 18x9.5 et45 wheels and project out where a 20" wheel will sit. It will be close.

You won't have any inner fender or strut clearance issues with 20x9.5 et45

 

[oldVOR]

20x10" at all 4 corners, +48mm offset, no steering stops, no rubbing.

Actually, you do have steering stops, installed at the factory to fit the wider wheels w/deeper backspace found on GT500's

 

[06 T-RED S/C GT]

The LCA curves toward the rear mount and there may be more of a clearance issue with 20" wheels. Alot depends on the build of the car. '05-10 base V6's have no steering stops, '05-10 GT's have the thinner steering stop and '07-10 GT500's have the thicker steering stop.

I'll measure my son's '05 with the SVT/FRPP 18x9.5 et45 wheels and project out where a 20" wheel will sit. It will be close.

You won't have any inner fender or strut clearance issues with 20x9.5 et45

After you brought to my attention about the thinner steering stops for 05-10 GT's along with your SVT 18x9.5 hitting the back leg of the LCA's.. I'm also very concerned about clearance issues with the LCA's as well..

In the meantime, I'm really grateful for willing to going through the trouble in measuring your son's '05 for clearance with his SVT 18x9.5 et45 wheels and hopefully this will provide an estimate as to where a 20" wheel will sit..

 

[06 T-RED S/C GT]

Norm,

3/8" sounds normal for old-school steel wheels.
Most modern alloy wheels are closer to 5/8"

I don't really know for sure if the lip/flange is 3/8" or not.. As the Steeda tech mentioned in general the lip/flange adds about 3/8 of a inch to the 6.521 calculation
So it will be around 6.8 to 6.9.. IMO it seems he's making an assumption, as he didn't have access to a wheel for taking an actual measurement..