MT Drag Radial pressures

[DTL]

I've got 275/60-15 ET Street Radials on 10" wheels right now and I'm trying to dial the pressure in. I've always run DRs at around 18psi on race cars, but I'm having ssues with my Mustang at this pressure. My car is a '13 GT, manual trans. with 100hp of nitrous on a progressive controller. It has rod-end suspension, LCA brackets, etc. Right now, 18psi doesn't work a lot better than the 25psi I drive it around on. Should I go against what the MT Reps. say and go even lower? Anyone have any guidance? Another local guy runs a 315 MT radial all the way down to 11psi, but that's sounds a little nuts to me. Thanks!

 

[Godzirra]

I never could get my manual car to hook on radials, much less my nitrous. I went to a bias ply slick. Aka et street. My car on stock suspension and full adjustable everything with spherical bushings both blow radials off. But I've taken radials down to 13psi before

 

[DTL]

If I ease it out and don't shock the tires, they seem to do ok, I'd just like to get more aggressive with it. A little delay in the controller really helps.

 

[psfracer]

On the M&H 325/50/15s I used to run, they liked 15psi.

 

[808muscle]

On DRs I run 17.5, my buddy runs 15. Are you doing a huge burnout? I need too or they dont hook.

Those bias ply ET Streets stick like glue and are a better drag tire for higher HP cars IMO.

 

[firestang70]

On my MT 3v on nitrous I ran between 12-14psi. Any more it would spin. Every car is different. I never had an issue running those pressures. On my 11 AT I run 14-16 depending on conditions.

 

[Sprayin Blue 3V]

I run 14, but that's on a bias ply ET Street. With a banger car you should always use a bias ply and not a radial if you wanna dead hook.

 

[fdjizm]

When I had et street radial II's I was doing pretty good with 15 psi cold.

 

[NotQuik]

Play with it and see what works best for you. A member on here suggested 11.5 before my spring swap when I was having issues and it helped. I run 12-13 now and that seems to work best with my fairly stock suspension and underpowered engine.

 

[daveyboy]

I race with guys that run 9.5 to 10 PSI in theirs

 

[fdjizm]

That sounds way too low for a radial tire, but I've seen stranger things.
Also at that low pressure you're going to start wagging that ass at the top of the track.

 

[DTL]

Thanks for all the good suggestions and combo examples. One thing I'm seeing in common is that I can (and need to) try some lower pressures. Thanks!

 

[NotQuik]

That sounds way too low for a radial tire, but I've seen stranger things.
Also at that low pressure you're going to start wagging that ass at the top of the track.

I'd agree if it weren't a stiff walled tire. When I was younger I quickly learned that little air pressure on a bias ply slick with a slow car doesn't mix.

Honestly, I've heard of 9-10 psi on dr's as well. Fortunately even with my turtle, I've never experienced any tracking issues.



Good luck OP, be sure an post back with your results...

 

[GT.350-R]

With my old M/T radials I had to run 11.5psi to get it to hook.
With the new Radial Pro's, I run 14.5 psi.

 

[daveyboy]

That sounds way too low for a radial tire, but I've seen stranger things.
Also at that low pressure you're going to start wagging that ass at the top of the track.

Yup I have heard them mention that too

 

[dysan]

When I was running the MT 325/50/15's depending on what power I pushing I would be anywhere from 14.5 to 15.5 but I was not a fan of those tires. I run M&H 325/50/15's now and they are much better. I run my current ones at 15-15.5.

 

[JDCoon]

On my gt500 with the Pro radial 275/50 MTs I run 17.5 to 18, same as I run in the wifes roushcharged 5.0 with 325/50s MTs, both auto cars. One friend with his 11 5.0 and stick with the pro radials runs 17.5-18 as well. A lot has to do with how hard you launch the car and the weight of the car. Have some one watch your tires on a launch and see what its doing.

 

[BMR Tech]

We run 275/60-15 MT......and we always run 16-18 psi.

We typically start out at 18 and work down if necessary.

On a stick car, I would start at 16, and work down.

You want as much give as possible on a stick car, so you will typically want to run them below what the "norm" is. This is proven by what GT.350-R stated above, his car is manual trans and he leaves the line very hard.

 

[mr. anderson]

I think another question is what are your best 60' with the tire pressure your running. I'm still trying to figure mine out. I can't get over 4,500 rpm without blowing off the tires. I've only had 3 runs at the track with the M/T drag radials, but my best is a 1.69 with 12 psi. any more rpm with a quick slip of the clutch results in pure tire spin. I'm sure I have a low 1.6 if not a 1.5 with them we will see. definately have to experiment more.