The Stovebolt Site Forums The Shop Area General Truck Talk Mixing radial and bias ply tires

I have 8-17.5 bias ply tires on my C-30 dually flatbed and the front tires are worn and the rear have decent tread but are very old. I have been collecting these obsolete tires trying to get together a decent set and I have found 6 radials that are decent but I also have 2 brand new bias ply. Any thoughts from you all about running the bias ply on front and radial on the rear? The truck is mainly a weekend around town driver, thanks.

At one time many tractor trailers had bias on the steering and radial on the drivers on the trailer because the older drivers, me included, didn't like the feel of radial tires on the steering axle. You cannot mix radial and bias on the same axle, but my rigs logged millions of miles in the late 70's until the early 90's with bias on the steer and radials on the drive and trailer.

that's great to hear, thanks!

Jeremey -- Crenwelge is old school and a wealth of knowledge (been there and done that, etc, etc). If he says it, you can believe it.

Anyway, so asking about mixing bias ply and radials reminds me of a sea story. There I was, helping a buddy get all his collection of trucks home from a local show. So I end up in the convoy driving a '70 IH 1-ton dump truck with a Model A pickup on a trailer. Only, the week before, one of the other guys had borrowed the dump truck, had a flat and hadn't told anyone yet that one of the front radials had been replaced with a bias ply spare...

Needless to say, going above 45 MPH was a hair raising experience and one that I don't care to re-investigate anytime soon. You can't imagine how close I came to turning two beautifully restored vintage vehicles (and a trailer) into a blood-spattered tangle of scrap metal.

Oh, nd I had no idea why the rig was so unmanageable until after when I mentioned it and the offender fessed up ... I almost came close to fisticuffs ...

Nice! Glad nothing got broke including the other guys nose ha!

Back in high school I had a 1970 Nova and ran radials on the front and bias ply tires on the rear. It was squirrelly when cornering because of the different sidewall characteristics.

Once I scrounged up enough money I went with radials on the rear.

Some one else my be able to explain it better. If you were to change to radials on front you may have to get alignment done so the radials would wear properly. Staying with bias on steer you save that expense if you are having no wear issues.

I once put radials on the back of a '57 Froid I had & kept bias on the front. They didn't stay on long, squirliest thing I ever drove.

My dad mixed them on a car one time. The results were "squirly" as Tiny mentioned. From the early commercials about radial tires I remember them stating that the bias ply tires will bounce vertically (or UP), and the radial will absorb the bounce by flexing horizontally (or OUT) via the sidewalls. It was always considered taboo to mix radials with bias ply tires.

Radials tend to need less toe in, not really a big deal to set.

Same thing here Tiny, I had a VW bug with radials on the rear and bias fronts.
Here you were allowed to mix bias and radials but not on the same axle,and as long as the radials were on the driven wheels.
A road trip along the winding roads on the west coast in the wet was the scariest thing ever!
Can you say understeer.......

there is a reason most tire stores will not mix tires on your car. The worst case it will cost you another $300 to get 2 more tires, pretty cheap for the safety factor if you ask me. I just went through all this I had 2 excellent bias ply tires, and was trying to get 2 more bias ply, it turned out to be $200 more for radials of the proper size and look I was looking for (7.00-15) If you are going to go cheap on something, cheap out on wood for the bed or seat covers, not safety related items. All told I spent $750 on tires and will be set for the next 10 years probably. Sure wish I knew how to post pictures, but on 1-29-12, in general truck talk, I posted a picture of the tires (my wife helped me, she is sleeping now) under "update on 15" wheels and tires"

Jeremey's truck is a dually on which it is perfectly safe to have radials on one axle and bias on the other.

Forgive me for reviving an old thread;
Cant find any biased 8.25 x 20 biased ply tires, (shy of china made which are almost three inches shorter tallness wise) but did pickup a pair of cheap half worn front radials.
Do you folks see any fresh issues with them on the truck front with biased ply on the rear?

Was gonna buy all six from china but they look so crappy on the truck as they are so short..

You should be careful running old radials...check the date code...how old are they?

You didn't say what year and size your truck is, but the 900x20 is the next size up...they might be easier to find if they fit your fenders.

Mike B

In recounting all these old bias/radial horror stories, I think many of us have forgotten how when radials were first introduced that they felt extremely squirrely to those of us who'd spent our driving lives with bias plies. The flexible sidewalls of radials felt loosy-goosy compared to the stiffer sidewalls of bias tires.

John, The rolling resistance is different for bias-ply vs radial ply tires so do not mix them. Doing so will result in some very strange handling characteristics (ask me how I know - 50 years ago and never again).

I have no driving experience with the mixture of bias-ply and radial tire, but as an automotive technician and a one time holder of a ( in Canada) MVI license ( Motor vehicle Inspection). That tire combination is not even legal. No debate. Can't even find a tire shop that would even do it, and if one brought a vehicle in with said combination for any work tire or otherwise,they wouldn't touch it..either all bias or all radial . From a legal aspect, be in a accident with a death involved or very serious injuries, all vehicles would be mechanically inspected, and whether the vehicle with mismatched bias/ radials was the cause of accident or innocent casuality, it be deemed unsafe and who knows how that would go for the owner..
All my vehicles ( old and new)have good tires on them. Safety is to important to cheap out on and be scrounging around trying to find a half decent set to tires to put on. I have a friend who does that,he can afford to buy new tires, just chooses not to..makes no sense. If you can't afford new tires for your truck, it doesn't belong on the road.

Radials and bias ply mix = SCARY to drive!!!