2008 alcoa shelby gt 500 KR wheels
06-05-2015, 07:30 AM
#2
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Not enough information, need wheel diameter, width, offset, and tire profile. I can't find this information in my own brief search.
But I can tell you that the wheels and tires from the 2008 'regular' GT500 will fit with no problems, because two sets of fronts (255/45-18 on 18 x 9.5 ET+45 wheels) is what I've been running on my '08 GT for maybe 20,000 miles out of the last 27,000. There's plenty of room up front for much wider stuff than 235/50's on 18 x 8.5's - 255/45's on 9.5-wide is kind of a baby step in what is possible.
Some people have been running 275/40's on those same wheels (all around), and I've got a set of 265/40's waiting for the last bit of useful wear on the 255's to get used up.
255/45's on 18 x 9.5 GT500 wheels
285/35's on 11" wide wheels (I can tell you that offsets are critical and different front vs rear, but I don't know the exact numbers)
Norm
But I can tell you that the wheels and tires from the 2008 'regular' GT500 will fit with no problems, because two sets of fronts (255/45-18 on 18 x 9.5 ET+45 wheels) is what I've been running on my '08 GT for maybe 20,000 miles out of the last 27,000. There's plenty of room up front for much wider stuff than 235/50's on 18 x 8.5's - 255/45's on 9.5-wide is kind of a baby step in what is possible.
Some people have been running 275/40's on those same wheels (all around), and I've got a set of 265/40's waiting for the last bit of useful wear on the 255's to get used up.
255/45's on 18 x 9.5 GT500 wheels
285/35's on 11" wide wheels (I can tell you that offsets are critical and different front vs rear, but I don't know the exact numbers)
Norm
Last edited by Norm Peterson; 06-05-2015 at 07:35 AM.
06-05-2015, 07:05 PM
#3
Thread Starter
Join Date: May 2015
Location: oklahoma
Posts: 4
More info
The wheels I am referring to are off a 2008 Shelby GT 500 KR made by Alcoa
they are a 18" rim 9.5 inches wide, I currently have the stock 18" 2008 bullitt rims on the car with the factory tires and wanting to run the Alcoa's the rims currently no not have tires on them but they had 285-40 18 rear and 225-45-18 on front which were the original tires on the Shelby I hope since I have already purchased these rims everything will be ok, what are the biggest tires I can run under the bullitt with these Alcoa rims? thanks norm!! what do you suggest? I do like the pics you provided!
they are a 18" rim 9.5 inches wide, I currently have the stock 18" 2008 bullitt rims on the car with the factory tires and wanting to run the Alcoa's the rims currently no not have tires on them but they had 285-40 18 rear and 225-45-18 on front which were the original tires on the Shelby I hope since I have already purchased these rims everything will be ok, what are the biggest tires I can run under the bullitt with these Alcoa rims? thanks norm!! what do you suggest? I do like the pics you provided!
06-05-2015, 08:10 PM
#4
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Join Date: Feb 2007
Location: state of confusion
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9.5" wheels are pretty much maxxed out with either 285/40's or 285/35's. The only 295 tire that lists a 9.5" wide rim being an acceptable fitment is 295/45, and is getting a bit pinched to fit.
Up front where you've got steering and strut clearances to contend with, I wouldn't go any wider than 275/40. As far as clearances are concerned, the extra lateral flexibility of a 285-wide tire on 9.5" adds to the fact that it's a slightly wider tire to begin with.
I'm afraid the fact that those wheels were made by Alcoa doesn't help me any. See if they have the offset molded or stamped on the back somewhere. Hopefully it'll be somewhere in the +43 to +45 mm range. For reference, the GT500 wheels that Ford Racing carries are +45's. Alternatively, offset can be figured out from the wheel's overall width (which will be about 10.5") and the backspacing, both of which are really easy to measure.
Norm
Up front where you've got steering and strut clearances to contend with, I wouldn't go any wider than 275/40. As far as clearances are concerned, the extra lateral flexibility of a 285-wide tire on 9.5" adds to the fact that it's a slightly wider tire to begin with.
I'm afraid the fact that those wheels were made by Alcoa doesn't help me any. See if they have the offset molded or stamped on the back somewhere. Hopefully it'll be somewhere in the +43 to +45 mm range. For reference, the GT500 wheels that Ford Racing carries are +45's. Alternatively, offset can be figured out from the wheel's overall width (which will be about 10.5") and the backspacing, both of which are really easy to measure.
Norm
06-05-2015, 09:55 PM
#5
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Join Date: May 2015
Location: oklahoma
Posts: 4
Norm, inside the wheel -ALCOA- Forged- MADE IN THE U.S.A. AF 1307 18X9.5J T-DOT
Machine Die #GA 0236623M 111708 and on the back rim is G6ES47 and on the front rim ALCOA FORGED SHELBY GT 500 KR that is everything I can find thanks for your help on this.....right now I think I will just run 255 45 18 all the way around? thanks again!
Machine Die #GA 0236623M 111708 and on the back rim is G6ES47 and on the front rim ALCOA FORGED SHELBY GT 500 KR that is everything I can find thanks for your help on this.....right now I think I will just run 255 45 18 all the way around? thanks again!
06-06-2015, 06:32 AM
#6
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Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
I can tell you that that combination will work very well in applications all the way up to entry-level track days (HPDE) or a bit beyond (you've been signed off to run solo).
If you measure the overall width and divide that by two, that will be very close to the wheel's center (may not be exact, as the inner and outer flanges could be of slightly different thicknesses). Measure the backspacing (from the outside of the inboard flange to the mounting pad) and subtract that half-width number from the backspacing measurement. That will be your offset, certainly as close as all but the very tightest wheel fitments (such as Vorshlag's 18x11 Forgestar fronts) would need.
Norm
If you measure the overall width and divide that by two, that will be very close to the wheel's center (may not be exact, as the inner and outer flanges could be of slightly different thicknesses). Measure the backspacing (from the outside of the inboard flange to the mounting pad) and subtract that half-width number from the backspacing measurement. That will be your offset, certainly as close as all but the very tightest wheel fitments (such as Vorshlag's 18x11 Forgestar fronts) would need.
Norm
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