frankieboo69 Posted July 16, 2008 Report Share Posted July 16, 2008 I hope this post is in the right place so no one talks bs or threatens to ban me ! I Noticed the GT500 have wider rear tires then the SGT'S and i was wondering if when i get done smoking the rest of the rubber off my tires if a wider tire will fit on our stock rims ? Something like the ones that come stock on the GT500's ? or would i need to change out the rims ???? THNX in Advance !!!!!! Link to comment Share on other sites More sharing options...
ShelbyPilot Posted July 17, 2008 Report Share Posted July 17, 2008 I don't think the 285/40's that come on the back of the Gt500 will work. Using the tire size calculator at 1010tires, I found the minimum wheel width for the 285/40 tire is 9.5". That is the width of the GT500 wheel. The stock Shelby GT wheel is 8.5" wide. You could use the GT500 front tire size of 255/45. According to the 1010tire calculator it is designed for a 8-9.5" wheel. There maybe other sizes out there that would work. Try using the 1010tire size calculator and stock tire sizes. You may find the answer you seek. Also, I am by no means a tire expert. Take my answers in that context. http://www.1010tires.com/TireSizeCalculato...p?action=submit Lastly another possible solution. Several of the GT500 guys have had their rear wheels widen up to 11". If you want to keep the stock look, that might be an option but I really have no foundation of knowledge there. Good Luck. Link to comment Share on other sites More sharing options...
tispco Posted July 17, 2008 Report Share Posted July 17, 2008 The 285/40 tires from the GT500 will not work on the SGT rims. The SGT rims are 8.5" and you need 9.5". The 255/45 front tires from the GT500 will fit on the stock SGT rims on all four corners. I swapped my SGT rims/tires for CT-R rims (wider - 9" front/10" rear) and GT-500 tires. The wider / stickier tires made a big difference in performance and looks with ride quality pretty much the same. Link to comment Share on other sites More sharing options...
slamarre Posted July 17, 2008 Report Share Posted July 17, 2008 Guys, FYI, Here is another web site with a graphical tire calculator. http://www.miata.net/garage/tirecalc.html Link to comment Share on other sites More sharing options...
69dejavue Posted July 18, 2008 Report Share Posted July 18, 2008 The 285/40 tires from the GT500 will not work on the SGT rims. The SGT rims are 8.5" and you need 9.5". The 255/45 front tires from the GT500 will fit on the stock SGT rims on all four corners. I swapped my SGT rims/tires for CT-R rims (wider - 9" front/10" rear) and GT-500 tires. The wider / stickier tires made a big difference in performance and looks with ride quality pretty much the same. Would this produce any speedometer error? Link to comment Share on other sites More sharing options...
ShelbyPilot Posted July 18, 2008 Report Share Posted July 18, 2008 Would this produce any speedometer error? According to the 1010tire calculator, about .5 MPH faster at 60 MPH for either the 285/40 or 255/45. If you have any questions about tire sizes, try this calculator. I use use it regularly. http://www.1010tires.com/TireSizeCalculato...p?action=submit Link to comment Share on other sites More sharing options...
tispco Posted July 18, 2008 Report Share Posted July 18, 2008 According to the 1010tire calculator, about .5 MPH faster at 60 MPH for either the 285/40 or 255/45. If you have any questions about tire sizes, try this calculator. I use use it regularly. http://www.1010tires.com/TireSizeCalculato...p?action=submit Sounds right to me. My speedometer seems correct and the diameter of the orginal SGT tire and the GT500 285 tire are virtually identical. The identical diameter was part of the reason I went with the GT500 tire sizes/brand. Link to comment Share on other sites More sharing options...
LuLu Posted July 18, 2008 Report Share Posted July 18, 2008 Seeking more clearance for a big brake kit, I changed out my OEM wheels for the FRP M-1007-188P wheels after I powder coated them black. 50mm offset vs. 45mm and spoke angle added about .5" clearance between the caliper and wheel spoke, and no one seems to notice the difference. However, the OEM wheel is 8.5" wide, and the FRP is 8.0" wide. This makes the OEM tires slightly taller, and my speedo is 2 MPH higher @ 70 MPH. Peek at pic #2 in my sig? Tire dynamics can be quite interesting... Link to comment Share on other sites More sharing options...
SGT/SC#0471 Posted July 19, 2008 Report Share Posted July 19, 2008 You mean you guys actually look at your speedometer? Link to comment Share on other sites More sharing options...
07SGT0546 Posted July 19, 2008 Report Share Posted July 19, 2008 Sounds right to me. My speedometer seems correct and the diameter of the orginal SGT tire and the GT500 285 tire are virtually identical. The identical diameter was part of the reason I went with the GT500 tire sizes/brand. While bringing up wheel/tire calculators, this is the best one I've found. It calculates odometer and speedometer differences, as well as lets you figure in offset, etc. http://www.wheelsmaster.com/rt_specs.jsp Link to comment Share on other sites More sharing options...
AstroDan Posted July 19, 2008 Report Share Posted July 19, 2008 While bringing up wheel/tire calculators, this is the best one I've found. It calculates odometer and speedometer differences, as well as lets you figure in offset, etc. http://www.wheelsmaster.com/rt_specs.jsp Cool. Does anyone know the offset of the stock 18x8.5? Link to comment Share on other sites More sharing options...
07SGT-C Posted August 16, 2008 Report Share Posted August 16, 2008 i'M runnin Nexen N3000 245/35/ZR20's on ECO type 107 on all 4 corners...not sure what offset as they were installed by dealer:/ pictures dont really do them justice, its a different look that kinda grows on ya...If i would of had the choice I prolly would of went with a set of the new shelby redlines or something but I'm happy with them for now Link to comment Share on other sites More sharing options...
LuLu Posted August 16, 2008 Report Share Posted August 16, 2008 Cool.Does anyone know the offset of the stock 18x8.5? I've seen the stock SGT wheel advertised as a 50mm offset, but I don't believe this is correct. I measured mine to be a 45mm offset, which is why they won't clear big brake kits offered by SPP. I opted for the 18X8 Ford Racing wheels used on the Marauder which I know are 50mm and gained the clearance I need for the BaerClaw kit on the front, though it hasn't been installed yet. BTW...The stock SGT wheel is 18X8.5 and should handle up to a 265 wide tire without sidewall complications. Hope this helps... Link to comment Share on other sites More sharing options...
GT500-07 Posted November 5, 2008 Report Share Posted November 5, 2008 Seeking more clearance for a big brake kit, I changed out my OEM wheels for the FRP M-1007-188P wheels after I powder coated them black. 50mm offset vs. 45mm and spoke angle added about .5" clearance between the caliper and wheel spoke, and no one seems to notice the difference. However, the OEM wheel is 8.5" wide, and the FRP is 8.0" wide. This makes the OEM tires slightly taller, and my speedo is 2 MPH higher @ 70 MPH. Peek at pic #2 in my sig? Tire dynamics can be quite interesting... Mac, do you know what the backset is on your wheels? Link to comment Share on other sites More sharing options...
39Mustang Posted November 5, 2008 Report Share Posted November 5, 2008 I hope this post is in the right place so no one talks bs or threatens to ban me ! I Noticed the GT500 have wider rear tires then the SGT'S and i was wondering if when i get done smoking the rest of the rubber off my tires if a wider tire will fit on our stock rims ? Something like the ones that come stock on the GT500's ? or would i need to change out the rims ???? THNX in Advance !!!!!! I got the optional 20" on my 08 GT/SC and the tire is 275/35/20 I think and since it sticks out a little further than the fender it looks un-Mustang like and wouldn't recommend anything wider. But then again the offset on the American Racing/Shelby wheel may be causing this. Link to comment Share on other sites More sharing options...
goakley1 Posted November 5, 2008 Report Share Posted November 5, 2008 #9 did you put an adjustable Panhard Bar on your Shelby??? If not, putting one on may fix the tires from popping out the sides, especially the drivers side. I, too, am putting 275/35/20's on the rear along with a Granatelli Panhard Bar. This will allow me to center the rearend under the car, thereby centering the wheels under it, too. Just my .02... Gary Link to comment Share on other sites More sharing options...
LuLu Posted November 5, 2008 Report Share Posted November 5, 2008 Mac, do you know what the backset is on your wheels? Offset = 50mm Backspace = 6.295" Link to comment Share on other sites More sharing options...
GT500-07 Posted November 5, 2008 Report Share Posted November 5, 2008 thanks Mac. been thinking of getting a set of the Shelby S1's (18"x9"), both SPP and American Racing say they will clear the GT500 big brakes. want to try these on the SGT with the Shelby Extreme brakes. the question is should I get the 40mm/6.5 or the 24mm/6.0? SPP says go with the 24mm so I can run wider tires. Link to comment Share on other sites More sharing options...
Shelby GT/SC 1685 Posted January 20, 2009 Report Share Posted January 20, 2009 Seeking more clearance for a big brake kit, I changed out my OEM wheels for the FRP M-1007-188P wheels after I powder coated them black. 50mm offset vs. 45mm and spoke angle added about .5" clearance between the caliper and wheel spoke, and no one seems to notice the difference. However, the OEM wheel is 8.5" wide, and the FRP is 8.0" wide. This makes the OEM tires slightly taller, and my speedo is 2 MPH higher @ 70 MPH. Peek at pic #2 in my sig? Tire dynamics can be quite interesting... Hello - I'm thinking about Marauder rims myself. I like the factory look. I found some that were widen by Weldcraft to 9.5" They appear to be added on the backside. I would think this would not give me any problems on my SGT. Any thoughts on this? You sound like you have lots of knowledge on this AWESOME site. Can I see a picture of your wheels on the car? Thanks in advance. Link to comment Share on other sites More sharing options...
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