Help with tires and tire pressure...Guys with 315s in here also

[Sonic04GT]

First off, what rear tire pressure are you guys running? I have 315s on the back with 3.73 gears and I still spin half way through second with 270rwhp. It annoys the crap out of me. I'm running around 33psi on Falken Azenis RT-615 315/30/18s.

Now, the main reason for the thread.

What size fronts are you guys with 18" 315s using? I have 315/30/18s on the rear 18x10s.

Currently have 275/35/18s on the front 18x9's that need replacing. I don't need something that wide on a daily driver so I'm thinking of dropping to at least 265s.

What would be a good match in sidewall height? Using a tire calculator it looks like a 0.07 difference between 315/30/18 and 265/35/18. Not sure if I want to get another pair of tires with a skinny sidewall though. Fender gap already doesn't look great as shown in the pics below.

I know someone with a couple 245/40/18s. How would these look on a 9" wheel? I don't autocross so I don't need anything crazy up front.

This is how it looks now. Already lowered ~1.5" with Steeda Sports.
http://i295.photobucket.com/albums/mm142/thealmightyhubbard/My Stangs/IMG_0317.jpg
http://i295.photobucket.com/albums/mm142/thealmightyhubbard/My Stangs/IMG_0318.jpg

Should I maybe step up to a higher sidewall front and eventually higher sidewall rears? The rears just went on not long ago so it'll be a while before I replace those unless I sell/trade. Might look kind of funny with the lower profile in the rear and higher sidewall in the front temporarily. I get fender-rub on the rear as it is. Need to get them rolled.

Gap doesn't look as bad from another angle besides dead on as shown above.

 

[Stumbaugh]

Spinning thru 2nd gear with 18" street tires should be nothing more than expected. My car has 315 555R's out back and if I powershift into 2nd on motor, it will spin a little.

To answer your question, I run 20psi in my rear tires.

 

[04GTMustang]

First off, what rear tire pressure are you guys running? I have 315s on the back with 3.73 gears and I still spin half way through second with 270rwhp. It annoys the crap out of me. I'm running around 33psi on Falken Azenis RT-615 315/30/18s.

Now, the main reason for the thread.

What size fronts are you guys with 18" 315s using? I have 315/30/18s on the rear 18x10s.

Currently have 275/35/18s on the front 18x9's that need replacing. I don't need something that wide on a daily driver so I'm thinking of dropping to at least 265s.

What would be a good match in sidewall height? Using a tire calculator it looks like a 0.07 difference between 315/30/18 and 265/35/18. Not sure if I want to get another pair of tires with a skinny sidewall though. Fender gap already doesn't look great as shown in the pics below.

I know someone with a couple 245/40/18s. How would these look on a 9" wheel? I don't autocross so I don't need anything crazy up front.

This is how it looks now. Already lowered ~1.5" with Steeda Sports.
http://i295.photobucket.com/albums/mm142/thealmightyhubbard/My Stangs/IMG_0317.jpg
http://i295.photobucket.com/albums/mm142/thealmightyhubbard/My Stangs/IMG_0318.jpg

Should I maybe step up to a higher sidewall front and eventually higher sidewall rears? The rears just went on not long ago so it'll be a while before I replace those unless I sell/trade. Might look kind of funny with the lower profile in the rear and higher sidewall in the front temporarily. I get fender-rub on the rear as it is. Need to get them rolled.

Gap doesn't look as bad from another angle besides dead on as shown above.

I would say for one its the lowering kit on the car causing the problem. I am not sure how good those tires are or not but if you are gonna just drive it on the street and its a DD then leave it at 33psi. I use to have nitto 555s not even the drag radial in a 315 with the kenne bell and it would bite in 2nd with a little bit of spinning. absolutely no change to tire pressure i left them at 35psi.

next i would ask how are you shifting the car...Powershifting or what?

 

[Sonic04GT]

Spinning thru 2nd gear with 18" street tires should be nothing more than expected. My car has 315 555R's out back and if I powershift into 2nd on motor, it will spin a little.

To answer your question, I run 20psi in my rear tires.

20psi daily driving?

As far as shifting, I have never power shifted any of my mustangs. I shift just as I would under normal driving, only much much faster

 

[Stumbaugh]

Yep, I keep them right at 20psi for DD'ing. If you go much more than that on the 555R's, it will wear out the center real quick. I have ran them at that psi since day 1, and have put around 12k miles on them and they are still not down to the wear bars.

 

[Sonic04GT]

I guess I'll try dropping to around 25-30 for now and see how that works. What pressure do you run up front?