Mixing bias plys & Radials ???

I've been following SAWZALL's post on bias ply and radial tires, but I didn't want to hijack his thread. I've heard it time and again about mixing bias ply and radials, but I would like to know the facts and the physics as to their use together.
I ran the last couple years with bias ply tires on the back and radials up front, and I don't know that there's a problem. I do have a vibration at 55-60 mph, but I thought it was a (slightly) out of balance driveshaft, and once I get past that speed it smoothes back out. Is that the tires?
What are the effects and the causes???

I don't know what sizes I have on 'er, but here's the match-up...




Thanks,


JOE

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Colder than a gut-shot bitch wolf, draggin nine sucklin' pups up a frozen mountain in a snow storm in the dead of winter, with a leg caught in a #4 trap and gaggin' on a mouth full of porcupine quills...



[This message has been edited by Junkyard Dog 32 (edited 02-25-2003).]

 

If ya feel the vibration in the steering wheel it's the front wheel balance, or out of round or shocks.
If you feel it in the seat of your pants it's the rear wheels or drive train.

 

Over here the only acceptable mix LEGALLY is radials on rear and bias on front. This is due to the different handling characteristics of each tyre ie a radial gives no notice and breaks away , a bias screams a lot and then lets go. Get them in the wet and the bias just let go not what you want on the rear when th efront is gripping. Only exception to this , again legally, is radials on the front with bias on the rear if the rears are 10inch or wider.

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Be slammed or damned!!

 

Kapri, do you realize you just made absolutely NO sense?

I was told many years ago that it's Radials up front bias in back, by an old-timer. But couldn't verify when I needed to last year cuz the old guy has retired and the younger guys of course don't know Shit!

I LIKE bias in the back because the Radials up front GRIP BETTER under most ANY situation. With the front gripping, The bias plys out back are handy in overcoming the BS factory engineered understeer and alowing you to slide the back better with either the gas or brakes without major "From Stock" changes in suspension or brake proportioning.

 

It is best not to mix radials with bias. The result can be unexpected squillery handling.

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seldom scene

 

Hey Kapri, knowing that you're as old as some trees, do you remember the safety ads they had on TV in Britain about the dangers of mixing crossplies (bias plys to Yanks) with radials?
I guess that was in the 60's and 70's when radials were becoming more commonplace.
Do you also remember the 'Weaver Bird' ads?

Junkyard, I never tried it, but I'm not sure it's such a good idea.

 

I had a friend with a '63 Chevy 3/4 ton that had 245/75R16s on the front and 16.5 bias plys on the rear... No problems.

I think on a fast car where handling is an issue it should be more of a concern. On an old truck that rarely sees more than 50 mph it probably isn't.

 

Everything always works "just great" till something goes wrong......Do not mix tire types.

 

I dunno the actual answer, but have a theory....

Has anyone here ever actually tried it? Nads says that there were commercials telling people not to mix'em up. Could this be a ploy by the Government and the tire companies to boost radial tire sales?

If your bias plied car blew a tire, you would need a new one. No big deal. But Wait....(insert sleezy salesman voice here)We don't have the right size bias ply tire for your car. And it's not safe to mix bias and radial. Tell you what we can do for you. We'll give you a great deal on 4 new Radial tires.

Like I said...Just a theory.

-Jeff Tanko

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It's an American tradition, like fathers chasing kids around with
power tools.

[This message has been edited by Bugman (edited 02-25-2003).]

 

6000 miles with no trouble, Firestone dirt trackers in the rear, radials up front.
chuck

 

Mixing radial and bias IS a bad idea. It's not something dreamed up by the tire companies or lawyers in their leather chairs. It true that people mix tires and have no problem at all, that's purely luck.

Typically you always want to put the lowest grip tires on the front, no matter what type they are. In all but the most extreme cases this means the bias up front. This holds true when replacing only two tires on your car. Always put the new ones on the rear. I realize that some people may think they need less performance on one axle to balance a car. This is far from the truth. In orer to balance a vehicle for handling you should always improve the axle you feel needs more grip.

As far as handling at the limit, radial tires win here for sure. Radial tires will give you a much more controlable limit than bias tires. They will communicate with you better and let you pass the limit then reel it back in much easier than bias tires which tend to rely heavily on compound only instead of the whole tire for it's limit performance.

In fact in all performance matters radial tires will win.

Now does this mean that everyone should run out and buy new radial tires, of course not. Performance isn't the only factor, in fact sometimes it isn't a factor at all.

 

For about forty years, thousands of hot rodders and drag racers have been using bias plies on the back and radials up front.

Hundreds of gassers used skinny radials up front and bias-ply slicks.

I'm not aware of any radials for sprint cars or Modifieds.

Every tire that has ever been made for pro-category Top Fuel cars, Funny Cars, Pro Mods, and Pro Stock cars that I know of are all bias-plies

You won't find anything that runs over 200 at Bonneville running radials. Any tires that I've heard of that got approved for running over 200 were all bias-plies.

Dave
http://www.roadsters.com/

 

Hey Joe-
Don't have much to say on the tire matter- I just wanted to say that it's nice to see a picture of the coupe up, and she's lookin fine!

Jake


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Six dueces on a Cadillac....the only way to fly!!

 

Kapri is correct: if you must mix the tires, put radials on REAR and bias on FRONT. If you put the bias on the rear instead, you are likely to get a fine view of the ass end of the car as it comes around the front...reason being, the bias tires are more slippery.

 

I've just got to add my 2 bits worth here.
If you're running the rig on the streets under no circumstances mix bias and radials !!!
The reason is that size for size radials have far suppeir grip on the road surface. In hard or panic braking situations the bias tires will break loose way quicker than the radials and suddenly you have two wheel brakes and BAD things are going to happen.A similar situation exists in hard cornering.
I'm building a very traditional A sedan but I'll guarantee, there will be radials on all 4 corners. I've been around for quite awhile now and I sure don't want it to end wrapped around a telephone pole or by being t-boned by some idiot driving a Beemer and dialing a cell phone at the same time.
Ted

 

if you build "traditional" it's a moot point.

on a hot rod with the big little setup the fronts need help in the traction department, so it would make sense to mix 'em up with the better gripping radials with the smaller footprint in front and the bias plys with the larger footprint in the back.

personally though, I run radials on all my cars

also, I'm surprised the hambster patrol hasn't chewed RV90619 a new one.

Paul

 

A radial tire is constructed to maintain a more rigid footprint on the ground. Like any tire, the footprint can be changed by changing the load or changing the tire pressure. Lower tire pressure allows the footprint to become distorted and causes traction to be lost.

A bias tire just is inferior and is easily distorted. At higher speeds, a lump is thrown out in front of the footprint because the tire stretches just before it hits the road surface. This causes temperature build up and increased wear as a smaller but similar wave is built into the footprint.

Because the bias tire gets less traction, it is possible that in cornering, it will tend to let loose traction first. So if the bias is on the rear, you get over-steer and if on the front, you get under-steer.

It is not true that radial tires do not communicate before losing traction. A good radial race tire on a twisty track, well heated begins to sluff off rubber in the turns and you can feel the car begin to crawl and actually increases the traction. You can correct for under or over steer and the crawl is quite predictable and useable.

Mixing bias and radial is asking for trouble. There is a limit to reasonable nostalgia if you plan on driving hard. And I'll be damned if I want anything that can't be pushed in the mountain curves.

 

For me it comes down to one thing.. what's the safest set up? I'm not completely afraid of taking risks, but as a Mom of a 6 year old, I try to minimize mine.

Mixing bias-ply and radials is a clearly stated no-no by Coker tires who clearly has a stake in the aftermath of the problems resulting from the failure of that set up.

Here's a quote from the Coker Tire website...

Q: I want to switch my bias ply tires to radials, but I have the original spare in the trunk that I want to keep. Can I use that bias ply tire as a spare?

A: Under no circumstance should you combine bias ply tires and radials. The results could be extremely dangerous. Even if you were only going to use the bias ply tire to get you to a rest stop, it would not be worth the risk. If you want a spare tire you should get one to match the others on your car. You could use the originals for shows, but not for driving.

Are they saying that because they want to sell you more tires or are they telling you that because they don't wanna be sued for not warning you? - you be the judge cause I don't really know the answer.

I run 4 radials and won't ever run bias-plys again now that I've driven on both. It was the first thing I did to my car and can't believe the difference it made with respect to ride and handling.

The important question to ask is if you're wrong and it compromises your ability to control your vehicle, is it worth totalling your nice car or worse-is it worth your life or someone elses who might be put in harm's way because you made the wrong choice?

It's not worth it to me, so I run what I perceive as safest. I'm sure some people disagree with my choice but I let conscience be my guide and you should let yours guide you.

With respect to being authentic or having a certain look- I'll go as far with preserving what I can within basic guidelines of comfort and safety. If having Radials makes my car less authentic, so be it. I'm more concerned with the way my car rides than with how it looks because I LOVE to drive!

I'm sure if I wanted to be more "authentic" on my Vespa I could ride around in a mod minidress and a open face visor helmet. Needless to say, I like where my face is and am not a big fan of road rash so I wear a full face and heavy jeans at all times when I'm riding. I'm sure I'd be cuter the other way but I'd rather not be dead or in pain...

Stacey

 

Take it from someone who makes his living in the tire biz...DON'T MIX TIRE TYPES!! We as a company have had seminars on the dangers of doing this exact thing. Also, with the thousands of different types of 'nostalgia' tires out there, ther is no reason to mix tire types.

 

OK, I have tried it! On my 51 F-1 pickemup. Radials up front bias out back. The end result, for driving on the streets and highways around here BAD JUJU. I thought I was gonna die. I have seen lots of drag cars do it but the strip is mostly smooth and flat, and the tires skinny and fat. Once I got bias back on front, I was able to drive safely down the freeway at 60 no problem. With the mix at any given time or speed, the truck had a mind of it's own and would start shaking violently, and was so hard to keep in the lane of choice. Once I reached home, I parked it till I got the right match, it was truely a death rod! And I will NEVER do that again.

 

[ QUOTE ]
...You won't find anything that runs over 200 at Bonneville running radials. Any tires that I've heard of that got approved for running over 200 were all bias-plies.

Dave
http://www.roadsters.com/

[/ QUOTE ]
Ya got me real curious there!
Is that because of some inherent quality or fault of the design that makes radials quit "working" at those speeds ( like the fact that they keep traction longer than bias but when they let go they let go all of a sudden) or is it because bias ply tires are all the tire makers have made in the past and still make in a quality that will stand the test? (if it ain't broke, technology.)
What do F1 IRL and Cart cars run? bias or radial?

 

[ QUOTE ]
Take it from someone who makes his living in the tire biz...DON'T MIX TIRE TYPES!!

[/ QUOTE ]

That's funny... Pete never mentioned that when he was mounting my bias tires for the back of my car!
When I had radials all the way around, my car handled like a dream, went down the road great, etc..., it just wouldn't hook up. Now I have MT ET Streets on the back (bias wrinklewalls), and it hooks better and handles like complete and total dogshit! it is less stable now at 45 mph than it used to be at 135, but hey, it keeps your adrenaline pumpin', isn't that what it's all about???

 

[ QUOTE ]
Ya got me real curious there!
Is that because of some inherent quality or fault of the design that makes radials quit "working" at those speeds ( like the fact that they keep traction longer than bias but when they let go they let go all of a sudden) or is it because bias ply tires are all the tire makers have made in the past and still make in a quality that will stand the test? (if it ain't broke, technology.)
What do F1 IRL and Cart cars run? bias or radial?

[/ QUOTE ]

That's a good question.

I know that Goodyear makes its G-19 race tires in both radial and bias styles for open wheel racing. Which is used more? I have no idea.

I also know that Skip Barber uses radial tires on its spec race car. Road racing on bias tires would be pretty stressful.

But those cars are designed for road circuits, including cornering and braking, not going fast in a straight line. I would think that that's the real difference, rather than radials "not working" above a given speed.

For what it's worth, here's a not-so-scientific destructive test on one Michelin Pilot Sport radial:
http://www.team.net/cgi-bin/wilma_hiliter/land-speed/200307/msg00023.html
It failed at 5,172 wheel RPM, or the equivelent of 417 MPH. However, this was also with no load or friction.

So... Do race cars that steer and brake a lot use radial tires, while those that mostly go straight use bias tires?

--Matt

 

[ QUOTE ]
[
What do F1 IRL and Cart cars run? bias or radial?

[/ QUOTE ]

All of them as well as Winston Cup run on radials. I'm guessing that no one makes a tire in the right configuration for LSR.

 

I've mixed them up with every possible combination, and raced like that. I can say that at 100mph, I didn't notice any differnce. Also, when the car starts to get sideways, radials suck. With the old street motor I had in my plymouth, that car was a hazzard with radials in back. With bias ply slicks, you know it's going to set crossed up before it lets go, and you have enough time to back out of it. With radials, forget it.

On the street I run M/T cheater slicks, with radials in front. Handles great. Dave

 

On the way to Sherman/Denison last year I hit something in the road and blew out one of my front bias-plys. So I went down Wal-mart in Sherman and bought two radials for the front. Driving down the highway on the way home was very intresting,the radials and the bias-plys didnt really want to go the same direction. WAS NOT A FUN RIDE!!
I dont want to have to try that again

 

So... it seems like it's split almost half anf half that it's dangerous or not. Could this be due to any other factors like the weight of the car or the shape of the road or something? Also, I know that going from bias to radials on my car, the toe-in changes from 1/4" in to 0. Could that have something to do with the handling aswell?
-Derrick

 

I tried it in 1974 on my 35 Ford coupe......small radial on front and wide oval L-60 Bias on rear.....scared me so bad I never did that again. it lets one end squirm and pins the other in place, starting a weaving action that if there were any play in suspension could cause a wreck....JUST MY OPINION-THO

 

I've got M/T ET streets on back, with skinny radials on the front of my 53. I don't see any troubles. I also ran bias rear streetslicks w/ radials on front of my 70 SS454 chevelle years ago with no problems. just my .02

 

when i was younger....WAY younger...my buddy ran skinny radials on the front and huge bias on the back of a 70 nova....the car hooked up like crazy,even broke alot of shit,but drove real stupid and scary,just like us