nfb: trying to help....

[95TransAm]

Hey wolf,
I run 97.47 PSI up front, and 7.86 PSI out back for traction of course. Just wanted to know if this is good, or should I inflate the fronts a bit more and lower the rears to get better 1/4 times?

[DeWynter]

245/50/16 30 PSI all tires

[wolfdogs]

Hey wolf,
I run 97.47 PSI up front, and 7.86 PSI out back for traction of course. Just wanted to know if this is good, or should I inflate the fronts a bit more and lower the rears to get better 1/4 times?

you run 97 lbs of air per square inch in a passenger car tire.......?

you run 97 lbs of air per square inch in a passenger car tire.......?


thats impossible

and

7 lbs per square inch in the rear? they would pop off the beads!!!

[wolfdogs]

what's wrong...I run 55 PSI on my TA

and 65psi in your head...........

[wolfdogs]

245/50/16 30 PSI all tires

ok...

for the O.E. tire at 30psi, the vehicle manufacture has determined that size tire performs the best under 30 psi which makes its load carrying capacity at each corner 1450 lbs . as we both know, thats plenty overkill given the curb weight of your car.

now, your 245/40r18 carries a max load at 35 psi of 1433 lbs. so to be the closest to what the O.E. prescribes.. you should run 35 psi.

now... at 32 psi, they carry 1354lbs, at 30 psi they carry 1272lbs.

now, remember... the O.E. does not figure all this on a straight down weight caused by the curb weight...factors such as body roll on cornering and body dip on accelleraton, braking, etc. all come in to play...

being that this new tire you run has a much lower aspect ratio (40 vs 50) the tendency for the sidewall to buckle under on hard cornering is greatly reduced..

here's where the weird stuff comes into play........ the design rim width for the 245/50 is 7.50", whereas on the 245/40 its 8.50...yet the 40 is 0.20" narrower in tread width... but only 0.04" taller than the 50.

so here's my recommendation: if you mounted those 18's on your factory rim...of 7.50"... run 32 psi. if you mounted them on a 8.0 or 8.5" rim... try running 30 psi... and just keep an eye on the outside of the tread to make sure its not wearing quicker.... if you experience too much body roll...inflate them to 32lbs or 33lbs.

[DeWynter]

so here's my recommendation: if you mounted those 18's on your factory rim...of 7.50"... run 32 psi. if you mounted them on a 8.0 or 8.5" rim... try running 30 psi... and just keep an eye on the outside of the tread to make sure its not wearing quicker.... if you experience too much body roll...inflate them to 32lbs or 33lbs.

Ok what about a rim sold as a 18" x 9" but in reality measures 18" x 9.475" inside of lip to inside of lip }{