07SGT5111 Posted January 24, 2015 Report Share Posted January 24, 2015 hey guys! So i decided to beat a dead horse and make my own thread in regards to this simply because i couldnt find one that directly relates and anwsers my questions. So for christmas i got a set of staggered Shelby Razors (gunmetal gray) not the silver american racing ones. 18x9 front and 18x10 rear. So my question is what size would work best with my car being lowered with the FRPP springs that Shelby installed on it? keep in mind the mods i have listed in my signature, specifically the 4.10's (i hear sidewall can effect speedometer/gearing). I have considered stock 2007 GT500 sizes but those are not lowered factory like the SGT. Anyone have these wheels with a good tire size setup? i really need some help here before i order some uber expensive Michelin Pilot Super Sports in the wrong size!! Like i like to say, Life is too short to learn from all of your own mistakes, might as well learn from others" Thanks in advance. Link to comment Share on other sites More sharing options...
TheKurgan Posted January 27, 2015 Report Share Posted January 27, 2015 It's hard to say what would be best because different manufacturers make tire sizes differently. You are probably going to have to get the calculator out and measure offset, back spacing, etc and then measure the wheel well to see what is the largest size you can fit. It is true that smaller tire height will effectively result in a lower gear ratio and throw off the speedo/odometer. Link to comment Share on other sites More sharing options...
2007_Shelby_GT Posted January 27, 2015 Report Share Posted January 27, 2015 18 X 9 on the front, 18 X 10 on the rear for me - American Muscle "Anthracite" Bullits originally with Nitto 555 tires, (size 255/45 front, 275/40 rear), recently changed tires to Mickey Thompson's, same size.I like the way this combo fills the wheel wells and the stock ride/handling hasn't been compromised. Sam Link to comment Share on other sites More sharing options...
39Mustang Posted January 28, 2015 Report Share Posted January 28, 2015 You are correct in ordering the Michelin's! Mine came with Nitto's very slippery and don't mean in the rain. Put the Super Sports on there was like peanut butter Link to comment Share on other sites More sharing options...
AstroDan Posted February 5, 2015 Report Share Posted February 5, 2015 18 X 9 on the front, 18 X 10 on the rear for me - American Muscle "Anthracite" Bullits originally with Nitto 555 tires, (size 255/45 front, 275/40 rear), recently changed tires to Mickey Thompson's, same size. I like the way this combo fills the wheel wells and the stock ride/handling hasn't been compromised. Sam Why use 10's on the rear if you're "only" running 275's? I would think at least 295's on rear... You'd need to calculate sidewall. Link to comment Share on other sites More sharing options...
2007_Shelby_GT Posted February 5, 2015 Report Share Posted February 5, 2015 Why use 10's on the rear if you're "only" running 275's? I would think at least 295's on rear... You'd need to calculate sidewall. No particular reason, just sometimes you go with what feels/looks right - I'd most likely change wheel/tire combinations if I were more track than street. Sam Link to comment Share on other sites More sharing options...
AstroDan Posted February 7, 2015 Report Share Posted February 7, 2015 I would think the 275's on 10"ers would look kinda like my fronts. 255's on 9.5". The rear 285's have a nicer "bulge", IMHO. My front slopes a little in... The rear is perfect on the 9.5! Link to comment Share on other sites More sharing options...
LuLu Posted February 8, 2015 Report Share Posted February 8, 2015 Well, yes...this horse has beaten but she ain't dead yet. Been through a lot of tires in the last 7 years, twice as much as y'all cause I got two SGTs. So, here is what I ended up with, and maybe why? OEM tire is a 235/50 on a 8.5" wheel. This results in a tire OD of 27.25", with a contact patch of 9.25" on the blacktop I settled on; Front: 255/40. Tire OD is 26.03" on a 9" wide wheel. Contact patch is 10.04". This size will drop the nose approx. 1.22" and that sounds like a whole lot of drop, but it's not. Ford Racing says our front suspension drop with the kit Shelby installed on the SGT is 1.5" under OEM height, but that's not true. Closer to 1.15", so, you have plenty of clearance, ground to point of contact. I tried larger sizes, but the frame rub on lock to lock turns was expensive. Rear: 295/35. Tire OD is 26.13 on a 10" wide wheel. Contact patch is 11.61". Again, I tried larger sizes, and each had it own share of problems and I settled on this size. If you favor a particular brand and the 295/ is not made by them, they'll have a 285/ and the difference is nominal. These sizes will add at least four inches of pavement hugging rubber to your program, without any ABS/TC issues and they look phenomenal. Speedo error is minimal too, 65 MPH is 62 MPH. Hope this helps, y'all be safe. Link to comment Share on other sites More sharing options...
tpow96 Posted February 8, 2015 Report Share Posted February 8, 2015 Well, yes...this horse has beaten but she ain't dead yet. Been through a lot of tires in the last 7 years, twice as much as y'all cause I got two SGTs. So, here is what I ended up with, and maybe why? OEM tire is a 235/50 on a 8.5" wheel. This results in a tire OD of 27.25", with a contact patch of 9.25" on the blacktop I settled on; Front: 255/40. Tire OD is 26.03" on a 9" wide wheel. Contact patch is 10.04". This size will drop the nose approx. 1.22" and that sounds like a whole lot of drop, but it's not. Ford Racing says our front suspension drop with the kit Shelby installed on the SGT is 1.5" under OEM height, but that's not true. Closer to 1.15", so, you have plenty of clearance, ground to point of contact. I tried larger sizes, but the frame rub on lock to lock turns was expensive. Rear: 295/35. Tire OD is 26.13 on a 10" wide wheel. Contact patch is 11.61". Again, I tried larger sizes, and each had it own share of problems and I settled on this size. If you favor a particular brand and the 295/ is not made by them, they'll have a 285/ and the difference is nominal. These sizes will add at least four inches of pavement hugging rubber to your program, without any ABS/TC issues and they look phenomenal. Speedo error is minimal too, 65 MPH is 62 MPH. Hope this helps, y'all be safe. +1 I have settled on this OD as well; bonus is that you can use the recent 18 inch spare tire/wheel that Ford produced for 19 inch wheel/tire combos. Although I don't use 19+ size diameters as they just add weight and limit tire choices. -Tom Link to comment Share on other sites More sharing options...
LuLu Posted February 10, 2015 Report Share Posted February 10, 2015 Added thought for those experimenting with staggered sizes. The difference between the front and rear OD cannot exceed 1.0". Greater will trigger ABS/TC issues, and maybe not immediately, but over time. The PCM/EEC counts tire revolutions per mile, counted over time. The ABS/TC will try to adjust, as it would with a low tire or a space-saver spare tire at play, but when it cannot adjust anymore, you will see PIDs and thrown codes. One of the alarms (and I do not recall which alarm) is stored in a section of the PCM/EEC our hand held tuners cannot clear, and a trip (and maybe a service charge) to a Ford dealership will be required. Carry on Gents, be safe. Link to comment Share on other sites More sharing options...
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