Pressures for normal radials

[azza11]

I have a mildly worked six in a XR wagon, i am running on the eighth, car weighs 1430 kg, my street wheels are 15x8 welds prostars with 255/60/15’s, i also have a pair of 185/14’s on my original steelies. I was going to fit these up when i drop the pipe, to me they have less roll out and should help it off the line by being smaller, wheels spin will not be an issue, not enough HP for that, the 14’s i figure should get me to the finish line quicker but i wondered as to what pressure i should run. I am changing the wheels at the track as car is to low to drive normally with the 14’s on, track only wheels.

[Giant]

I have used a range of pressures for the rears anything from 22 to 45 psi.
Fronts 50 to 55 psi.

Good luck and have fun

[dieseltrain79]

I found 22psi in my normal street tyres worked best . And yep 45-50psi in fronts .

[FPV GTHO]

What profile were your street tyres?

[Giant]

215 60 16
225 50 16

[dieseltrain79]

Mine were 265/35/18 .

[azza11]

My street tyres are 255/60/15, i have lowered the car with reset leaves and 2” lowering blocks, for the 15’s its as low as i could go with out being a major pain.

[azza11]

Proper gearing if i wanted to optimize trap speed and revs would be 4.11’s, but would be a pain on the highway, car has 3.5’s as standard. Seen a XP sedan with 200/C4, he races the eighth and hist the limiter just before the fin line.

[dieseltrain79]

Probably limiter in 2nd gear for 1/8th mile , not 3rd.

[azza11]

yeah i wish, its a 3 spd manual, will do 80 in second with stock 200 super pursuit and custom exhaust dropped, i am trying both on Sunday, got the big wheels, pipe up etc for a true street trim, then drop pipe, bolt on screamer pipe, 14’s and remove air cleaner, will get a good idea of what these changes do, bring on The Six Banger Nats

[dieseltrain79]

Depends on how fast it is as to whether it will run out of legs over the 1/4 .

18's should be up to 120
17's 130
16's 140
15's 150
14's 160

Rough guidelines , but averages show , lower in the Et range closer to the speed range .

Good luck .

[azza11]

i won my class on the weekend at The Six Banger Nats at Warwick, i ended up buying 175/70/14’s, ran 25 pounds of pressure, seemed to be good, with the 3.50’s it wasn’t super fast at the fin line. Eighth mile drags, my best ET was 12.66 at 53.75, stock 46 year old bottom end, head has been off once for ULP conversion, untouched car, dizzy, custom exhaust with 2.5 inch collector and screamer pipe, no aircleaner on these runs, havent even timed the motor, seems spot on. Consistent, 8 races, no loss’s apart from
2 breakouts, car went quicker when it was around 30 odd degree’s in the sun back to back runs.

[dieseltrain79]

That's awesome mate ! Well done .