I can't remember, but I don't think I have ever ran a car down the track with Radial front, Bias rear until last week (at least a fast car) & am wondering if the majority of my top end wandering issues is from the mis matched tires?

I've ran several cars on the street with Radial front/Bias rear combo's & never really had any ill handling issues, but those are generally stiff sidewall bias plys like a M/T INDY Profile.

My Road Runner now has 235/60 BF Goodrich Radial TA's up front & 26 X 11.5 Hoosier Quick Time Pros on back for track use.... Last week had rear pressure @ 18PSI, car went 118.4 MPH & was wandering all over the place from about 1/8 mile on, & then decides to do some wicked diving around when I let off after the stripe. I thought I'd make it a little better by trying 24 PSI since junk converter was'nt allowing it to hit tires hard on launch anyhow.... needless to say I let off around 1100' as I was wandering towards the timing boxes @ the traps. I only have a 7" wheel & with the 11.5's with more air actually reduces contact patch....

I ordered a set of 275/60/15 Hoosier Drag Radials this AM & will try those this weekend if weather cooperates. I have a new 4000 Stall PTC 9.5" verter coming at beginning of week, & am hoping I can get car to hook with the DR's once it is in.

I've had the car to around 110 on the street with the Hoosiers on & it feels way better stability wise, than it does at the track?? Dunno what is into it... Buddy of mine has a mid 11 sec '70 Chevelle that runs Radial fronts & M/T ET Streets on back & said his does similar wandering around, but he said his really only does it on deceleration...

I did'nt really want to try a bias front tire since I drive car every day on street I'd like to keep the Radial TA's on it, because they work well in the rain & taking corners @ speed..

Just wondering what everyone's experiences have been like trying to run 110+ MPH with radial front/Bias rear, especially with a wrinklewall rear tire....

Just feels like rear end is wandering from side to side real bad @ speed & I'm constantly trying to chase it with steering wheel. Not happy with it at all....

I've driven Radial front, bias ply cars before, some wander badly, some not so much. None of them have been as stable as my Radial/Radial Set up. I don't think i will ever put a bias ply on the rear of my car, unless it absolutely won't hook on the radials.

My father had some really bad rear wandering when he had radial front tires and bias ply back tires. He made the switch for bias ply front and rear and says the car handles much better. His car runs 11.40's around 120 mph. I raced my grandfather's Demon with radial front and bias ply rears and it handles great. The Demon runs 12.50's around 110 mph. I think the faster the car the more it is effected by mismatched tires.

That's probably the root of it. Wide 60 series radials in front will make it worse, than, say a narrow 70 or 75 series radial will.

One thing that makes it alot better is increase the air pressure in the front. Pump them up to the max, or maybe +5 or 10 psi beyond that and it will probably straighten up quite a bit. It will probably never be perfect but it should help some (at least it helped mine).

I bought a pair of bias front runners but have never tried them except a short time on the street. Big difference in stability with them w/bias rear.

My '71 'Cuda tended to follow seams in the road rather badly when driving with radial front and bias rear.

Very scary at times!

Ryan,
My dad has a 69rr that has a very mild 440 with a 4sp with radials in the front and m/t et slicks in back. It wandered all over the track and went 114mph. Had a similar issue with my old drag car dart, radials in front and bias m/ts in back. Went to bias in front also and could drive with one finger. Some cars can pull it off and some dont for some reason

Been 135 with 225/60 radial up front and 28x11.5 et street. It gets a little swayey if thats a word? but not nothing too crazy.

Sometimes - certainly not all the time - mismatched radial tires will handle very badly. My 3/4 ton truck came with bridgstones on it. When I needed to replace 2 of them I got a different brand of exactly the same size and load rating. The truck handles so evily that I took them back the next day and got a more expensive pair of a different brand and it handles much better but still not as good as it did with all 4 the same. I'll probably get 2 more new ones before winter. If 2 different but equivalent radials can handle that badly, I can't imagine what it would have been like if I had mixed in bias tires.

That said, I think 11.5" wide tires on 7" rims probably contributed alot to your wandering problem.

My bracket Challenger "wandered" on the top end with radial front tires for the short time I tried them No intentions of putting them on my current car. Just plain Hoosier frontrunners.

I've heard of only a couple of people who said that they didn't have any concerns with front radial tires at the track. Most do.

I have not seen any handling differences between bias play and radial drag slicks.

I run in the 115 MPH range with radials up front ( P235/60's ). If I try and pump them up ( over 35 psi ) the car gets squirrely. Seems to be best around 32psi. Run bias ply Hoosiers out back. I don't think there is any "connection" between poor handling at speed and running radial / bias tires as long as they are on different axles. I do think bias ply tires up front add stability at speed and radials are more sensitive to tire pressure than bias tires. When you are running a big old boat at speed you gotta make sure all the suspension and steering components are up to speed - so to speak.

DON'T MIX BIAS & RADIALS

Rickster

i run a radial up front (165/15) and slicks on the rear at the track and the car drives nice. i guess im the lucky one. its been a long time sence ive done it with a bigger front tire though

I don't know if the mismatched tires cause the rear wandering for me or not, but it's something to think about. My old truck has a REAL HIGH center of gravity and above 110 on the track it doesn't just wander, it gives you Religion. After half a dozen passes like that I now look like Moses, My beard is snow white. Dave

I ran a 26x10 on an 8" rim and had pretty bad walk on the big end running low 12s. One thing that made it alot better was when I quit trying to correct for it, steering it only made it worse. Oddly enough nitrous was a great fix for the problem, I guess it kept the tires wadded up for longer and helped out with the stability.

I never had any issues on the street with a radial front bias rear combo. I don't think I would want a bias ply front on the road, if the back end follows ruts and wanders(which it does sometimes) I sure as heck don't want the whole car doing that.

You also might check your toe settings, if its toed out a little it might wander around some and exagurate your problem.

My brother has quick time pros on his 68 cutlass with a 60 series radial tire on the front. It used to run high 13's with the 350 and drove pretty stable at those speeds. The few shakedown runs with the 455 has it in the elevens at 114mph +/-, and now it takes a lot more wheel action to keep it tracking straight on the top end.

He plans on going with either a taller and narrower radial or a set of bias skinnies soon. This car has yet to be maxed out and another 5-10 mph is only going to make it that much more difficult to handle.

Hoosier tires also follow the trucker ruts in the roads really bad. You have to inflate them up on the street unless you like moving the steering wheel constantly when driving on lousy roads.

I wonder if it's possible to make the car more stable by fiddling with the alignment some????

I run radial street tires up front and was running the Hoosier Quick Time Pro tires that were 29 x 11.5. The tread was just over 10" as the 11.5 is the width on the Hoosier tires. My 63 runs mid 11's from 114 to 16 and it would wander some on the top end but not real bad. I did notice it would really want to go with the lines in the street when driving on the street and I did not like that when in traffic. They also rubbed on turns as my suspension is stock location with stock body so I decided to try the Hoosier 30 x 9 radial slick. They dont ever rub and wow does it handle like a new car. The car went faster on them once I got it to hook on them and I have been driving with them on the street and they handle way better then any other rear tire I had on the car. The problem is no one makes a 30 x 9 drag radial ! I can only find a radial drag tire of that size in the slicks only and they fit perfect in my wheelwell. So I had the new radial slicks on an 8" wheel and I took the old pair that I had tried first and put them on a 7" wheel and have been driving them on the street since May. They handle so good I wont go back to the QTP tires. I just wish someone made a 30 x 9 drag radial. Ron

I've run bias plies & radials mixed both ways front & back. The only time I had the back end wagging on the big end was entirely due to bias-plies on the rear being run w/ too little air.

FWIW, when I run radials up front at the track I set 'em at 40-45 psi to keep the sidewall flex down. When I paired them up w/ bias-ply rear tires on the street, I also ran them that high to keep the car's handling better balanced.

I normally run my front tires at 42-45psi and my slicks at 12.5psi. Any less air in the slicks and it gets worse. I've had to abort passes by the 1/8 mile mark at times because it got so squirrely I was afraid of stuffing it into the wall or rolling it. Dave

All good info. Hopefully the Drag Radials cure it, I'm ashamed to say I don't think I've checked my front tire pressure since I put them on 4000 miles ago.....

Need to get the thing to drive straight & consistent so I can start tuning on it instead of chasing it around the track. I over-revved it on 3rd pass last week because I was chasing the steering wheel on the 2-3 shift & popped 2 pushrods out during valve float @ 6800-6900 (hydraulic roller, & did'nt have a chip in the limiter)