Madlock Posted December 12, 2010 Report Share Posted December 12, 2010 Forgive me for anything that may be laughably obvious to most others - that I'm only now beginning to learn, realize and understand. I'm finally preparing to pull the trigger on ordering my alternative wheels and tires for my 2011 GT500 with SVTPP to give myself an alternative to the F-1 G: 2's that make the car more everyday friendly - even during non-winter months. One of the biggest obstacles has been the lack of any kind of definitive reference that establishes the boundaries of wheel and tire size combinations that can be used without causing clearance issues- particularly given the extent to which there can be so many different S197 suspensions that lower the chassis to different degrees - particularly for vehicles with the SVTPP, as it affects some 3/4 of all 2011 GT500s. With respect to the SVTPP, one of the reasons I decided to order it was the 3.73 rear axle - not knowing just how easily certain things can be modified after he fact. If 3.73 is what I wanted most, I could've simply swapped-out the gearing and added the FR3 pack for much less money and drama because I could've decoupled everything from the damned F-1 G: 2's. As others have pointed out to me (which I hadn't fully appreciated at the time), the 3.73 merely gives back some of the quickness lost when going from a 27" diameter rear tire to 28". I'll be going to a 19" rear wheel. While I had been trying to remain as faithful to the original 28" tire diameter (both to keep the car as close to its factory stance as possible and to use the additional sidewall to soften the ride a little and gain a bit better power application) and my thoughts were largely focused on not exceeding the factory width or diameter, I'm now beginning to think about different combinations, including final drive gearing - without setting all the factors of the equation in motion against each other. So, I'd appreciate any helpful thoughts about the following two propositions. On a 19" wheel, what's the smallest tire diameter I can get away with - given that any diameter reduction COULD enhance quickness by effectively increasing the final drive ratio effect - but knowing that the car has already been lowered by virtue of the SVTPP suspension setup. I don't want to be using the pavement to polish the bottom of the differential. I've also begun giving thought to a far more radical path. I know the FR 4.10 gearing is mostly meant for dragging and would probably make shifting during everyday driving fairly cumbersome - not to mention being absolutely brutal in terms of fuel economy. First gear would pretty-much become a bit of nostalgia. The theoretical up-side would come from the fact that in the same vein that I could reduce the rear tire diameter to gain-back some of the quickness the 3.73 gearing loses by the 28" OE tire, I could (theoretically) increase the rear tire diameter to offset some of the huge differential between the 3.73 to 4.10 gearing - while simultaneously gaining even more sidewall for an even more compliant ride with an even-better ability to connect the crankshaft to the pavement. For this scenario, I'd need to know the largest diameter a 2011 chassis could accommodate slung on the SVTPP suspension set-up. The challenge for me (particularly with the second scenario) is the difference between the math that works and the real world that sometimes gets in the way. To fully offset a 3.73 to 4.10 gear change, a tire would have to turn 676 times per mile versus the OE 724. But to recreate the same kind of giddyup a 3.73 normally gives versus a 3.55, a tire would need to turn about 690 times per mile, something that can be almost be achieved with a 29" diameter tire - for which a reasonable selection of tires actually exists, particularly if I were to consider keeping the OE 20" wheels on the rear. For example's sake, a 285/40-20, 285/45-19 or even 305/40-19's would be close enough for government work. So, I suppose the bottom line is that I'd need (like) to know both how tall, and how short a rear wheel diameter a 2011 GT500 SVTPP can accommodate without shooting myself in the foot. I'm not necessarily interested in simply going wider for the sake of going wider, particularly because so many tires this wide already have a tendency to hydroplane, but I'd also appreciate knowing just how wide a person can go under the same circumstances (presuming equivalent relevant offsets to the factory setup). I'd appreciate any helpful insight - even if I happen to be heading toward the deep-end. Link to comment Share on other sites More sharing options...
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