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Wore out the 275/35 Super Sports. I got 20k miles out of them, but the last 3-4k was scary. I always felt the car was under-tired from the factory. A car weighing 4000 lbs with 467 hp needs more than 275s. I routinely overpowered the tires. No traction from a dig and power slides around a tight curve is fun, but not all the time. I bought the VMR 19x9.5 ET 33 and 19x10.5 ET 35 with the intent to remain as close to stock circumference as possible. I replaced the Super Sport with PS4s. These tires are huge! They are only 1.2 inches wider than the 275, but they look even bigger. I was a doubter that they would fit without rubbing, but I was wrong. In the pics below you can see when the rear is compressed while going up my driveway, that i could actually lower the car quite a bit and still not rub. I spent some time on some on San Diego's worst streets and dips and no rubbing whatsoever. Even though the tires are practically flush with the wheel well, they camber inward as you lower the car. I know it sounds strange, but a rear suspensions with -1.5 camber does not travel straight up and down, It compresses at an angle depending on your camber settings. I could stand to lower the rears about .5 inch, but I'll wait on that. As far as driving, the car should've came with 295s at a minimum. First of all, the 275s were stretched quite a bit on the 10.5 wheels. The 305s are pretty flush and actually makes the rear wheel looks more concaved which it is. I can feel the rear contact patch even more and I get some tramlining on some roads. A little more understeer due to wider stagger, but easily remedied via throttle. The power is put down without hesitation; from a dig and roll. Its like everything was taken up a notch. I can give it 3/4 throttle from a stop and not chirp. The rear just squats and the car rockets forward. Braking has increased as well. The TVD reacted very well to the extra rubber. I can now add moderate throttle mid turn and power out. In sweeping turns, understeer is eliminated by simply adding throttle. Around the city, I was afraid to go into a corner as hot as I did with the Vortech G35 with fully modified suspension. Despite the weight, the brakes are up to it, the tires not so much. As soon as I got mid turn, the rear would step out and VDC would engage. Now the rear sticks and I can get on the throttle sooner. The TVD with 305s begs for turns now. No power slides so far. something tells me these tires have a far greater holding threshold than I am willing to test on the street. By the way, going up the driveway causes front end to raise, so I am not in of a drop flush, but I plan to add fender arches no rubbing during compression
Wore out the 275/35 Super Sports. I got 20k miles out of them, but the last 3-4k was scary. I always felt the car was under-tired from the factory. A car weighing 4000 lbs with 467 hp needs more than 275s. I routinely overpowered the tires. No traction from a dig and power slides around a tight curve is fun, but not all the time. I bought the VMR 19x9.5 ET 33 and 19x10.5 ET 35 with the intent to remain as close to stock circumference as possible. I replaced the Super Sport with PS4s. These tires are huge! They are only 1.2 inches wider than the 275, but they look even bigger. I was a doubter that they would fit without rubbing, but I was wrong. In the pics below you can see when the rear is compressed while going up my driveway, that i could actually lower the car quite a bit and still not rub. I spent some time on some on San Diego's worst streets and dips and no rubbing whatsoever. Even though the tires are practically flush with the wheel well, they camber inward as you lower the car. I know it sounds strange, but a rear suspensions with -1.5 camber does not travel straight up and down, It compresses at an angle depending on your camber settings. I could stand to lower the rears about .5 inch, but I'll wait on that. As far as driving, the car should've came with 295s at a minimum. First of all, the 275s were stretched quite a bit on the 10.5 wheels. The 305s are pretty flush and actually makes the rear wheel looks more concaved which it is. I can feel the rear contact patch even more and I get some tramlining on some roads. A little more understeer due to wider stagger, but easily remedied via throttle. The power is put down without hesitation; from a dig and roll. Its like everything was taken up a notch. I can give it 3/4 throttle from a stop and not chirp. The rear just squats and the car rockets forward. Braking has increased as well. The TVD reacted very well to the extra rubber. I can now add moderate throttle mid turn and power out. In sweeping turns, understeer is eliminated by simply adding throttle. Around the city, I was afraid to go into a corner as hot as I did with the Vortech G35 with fully modified suspension. Despite the weight, the brakes are up to it, the tires not so much. As soon as I got mid turn, the rear would step out and VDC would engage. Now the rear sticks and I can get on the throttle sooner. The TVD with 305s begs for turns now. No power slides so far. something tells me these tires have a far greater holding threshold than I am willing to test on the street. By the way, going up the driveway causes front end to raise, so I am not in of a drop flush, but I plan to add fender arches no rubbing during compression
Nice. With 305 30s in the rear, what did you put on the 9.5s up front?
I'm still on the original 255/30 Super Sport. When the time comes, I'll either stick with stock size if there isn't too much understeer or move up to 265/30. The latter requires me to adjust coilovers and get an alignment. I'll be losing .4" of sidewall
No alignment done. The rears are already set at -1.5, so that helps the 305 to tuck. No height adjustment needed. I only lost .2" of sidewall. I still have the original Super Sport 255/35 on the front. I just passed 20k miles. The 305 rears are Michelin Pilot 4 (PS4). I believe this is the replacement for the Super Sport, which has dwindling supply and actually cost more. I also considered PS2, but felt the PS4 was a better all around tire.
Nice! I wish I went 305's as well. Anyways, how are your RSR coilovers performing?
i've had my RSR on for a year and 10k miles. Still holding up fine. I thought the 36 way adjustability was overkill, but you really can fine tune your setup. Fronts are easy to do, rears requires removing trunk trim. Adjusted about 4 times until I came up with current settings; 31 front, 22 rear. This is a little more stiffer than stock. Remember, rear springs are stiffer, even in stock form. No noise yet either. They are probably not the most hard core setup for track use. I've used RSR before for springs for my G35 and the quality was good. I am patiently waiting to see if Blistein will make a coilover for the F.
I always felt the car was under-tired from the factory
Yep, if you felt the RCF is undertired what are you feelings on the ISF 225/40/19 fronts and 255/35/19 back on 8s and 9s. Extremely undertired IMHO. I am running base RCF wheels (my favorite design, BTW), on my ISF. I have 255/35/19 and 295/30/19 Bridgestone Potenza S-04 tires. Luv the looks of the wheels and luv the performance of the S-04. My ISF now handles like a slot car. Suspension is stock except for RRRacing front A-Arm bushings (USRS) and F-Sport rear sway bar.
Yep, if you felt the RCF is undertired what are you feelings on the ISF 225/40/19 fronts and 255/35/19 back on 8s and 9s. Extremely undertired IMHO. I am running base RCF wheels (my favorite design, BTW), on my ISF. I have 255/35/19 and 295/30/19 Bridgestone Potenza S-04 tires. Luv the looks of the wheels and luv the performance of the S-04. My ISF now handles like a slot car. Suspension is stock except for RRRacing front A-Arm bushings (USRS) and F-Sport rear sway bar.
Lou
do you think the 305 30 19 will fit on the stock rear 10" wheel?
08-16-17, 06:57 PM
305/30/19 Finally
225/40/19 fronts and 255/35/19 back on 8s and 9s. Extremely undertired IMHO. I am running base RCF wheels (my favorite design, BTW), on my ISF. I have 255/35/19 and 295/30/19 Bridgestone Potenza S-04 tires. Luv the looks of the wheels and luv the performance of the S-04. My ISF now handles like a slot car. Suspension is stock except for RRRacing front A-Arm bushings (USRS) and F-Sport rear sway bar.
