Radial tire chatter

[Floyd Staggs]

I put a set of MT Street Radials on my truck and have developed tire shake on the launch in warm weather. I have increased the 60 ft times and made better reaction times but when the track warms up I get severe tire shake. I started at 15 lbs, reduced it ti 14 1/2 lbs and got my best 60 ft and best et ever. That was @ Super Chevy @ Fontana and the air was great. The next weekend it got hotter than hell, 99-100 degs air and I started to get tire shake as soon as I let off the brake. I footbrake a 4000 lb P.U. that runs 10:70-10:80 on pump gas. I do like the tires but we are approaching summer and I'm going to break something with the tire shake. What am I doing wrong?

[Tom Goldman]

Floyd, The owner of the dealership I work at has a low 11 sec.Pro Street AMX . ...During the hot weather months we have to switch to bias plys to avoid spinning or shaking. ........The McCreary DOT bias ply tires we run are almost as fast as the drag radials, about .05 slower, but we can hook every time.....Tom

[Freddie]

We run ours as low as 13# in the summer on our Mustang.. they still spin alittle but dont shake.

[CPOlesen]

Radials don't like low air pressure. try 20 lbs and if your 60' doesn't change go up.

[Floyd Staggs]

Originally Posted by CPOlesen

Radials don't like low air pressure. try 20 lbs and if your 60' doesn't change go up.

I was trying different pressures but we got into eliminations and I need the points. I had another thought. I might have my shocks set too soft.

[donald j raiser]

what size rim?, what size tire? stick or auto? i may be able to help.
dj raiser
SS/GTAA

[Todd Geisler]

Most of the time I see cars with tire chatter with radials, it's due to either too low of air pressure, or the shocks out back are set too soft.

My car likes the back end very stiff, both rebound and compression.

[Floyd Staggs]

Originally Posted by donald j raiser

what size rim?, what size tire? stick or auto? i may be able to help.
dj raiser
SS/GTAA

Don, The rims are 10" wide, the tires are 325X60R15 MT. It's a turbo 400.
I'd appreciate the help.

[Floyd Staggs]

Originally Posted by Todd Geisler

Most of the time I see cars with tire chatter with radials, it's due to either too low of air pressure, or the shocks out back are set too soft.

My car likes the back end very stiff, both rebound and compression.

Todd, the backend is already stiff with 250 lb springs but I do have the shocks set soft. Like I said, I started at 15lbs, dropped to 14 1/2 in the cool weather and was doing great. 1:452, 1:453, 1:452 60 fts. 2 weeks later it got hot and first I lowered the pressure to 14 then I raised it to 16. The last pass I eased it out trying to win the race and broke out by .005 so I didn't really get to try the highr pressure.
Thanks for the response.

[Todd Geisler]

Originally Posted by Floyd Staggs

Todd, the backend is already stiff with 250 lb springs but I do have the shocks set soft. Like I said, I started at 15lbs, dropped to 14 1/2 in the cool weather and was doing great. 1:452, 1:453, 1:452 60 fts. 2 weeks later it got hot and first I lowered the pressure to 14 then I raised it to 16. The last pass I eased it out trying to win the race and broke out by .005 so I didn't really get to try the highr pressure.
Thanks for the response.

That's the same size tire I run. I've run the BFG's, M/T's, now the Hoosiers. All have worked with 18 psi cold, as high as 19.5 psi hot. Typical usable range for me is 16 to 18 psi. I can't remember ever going to 15 psi.

I run 120 #/in rate coil springs out back (stock type coils) and double adjustable shocks. You need the firmness to come from the shock valving (control), not so much the springs themselves.

My car has 60's a best of 1.289 footbraking, mid 9 second naturally aspirated 454 bbc, th400, 6000 flash 8" converter, th400, 4.33 gear.

Hot & greasy tracks are a big challenge for the radial tires. For this reason, I now have a second set of rims with a pair of 10.5 x 28 Hoosier stiff sidewall slicks for when conditions are at their worst.

hth
Todd