Mixing bias & radial tires

[AC-Craig]

Sent: 6/3/2003 1:52 PM

A year ago, I replaced four of my tires with bias ply because I couldn't afford to replace all six and I understand you can't mix radial and bias ply. I put two new tires on front and two on the rear. If I put the four bias on the rear, can I put two radials on the front? Has anyone done this? 

[denisondc]

Sent: 6/3/2003 5:34 PM

The conventional wisdom is not to put radials on the front with bias play in the back of YOUR CAR, because the radials have a lower slip-angle than do bias ply; that is the angle between the plane of the tires theorhetical track and the actual direction the center of the tread takes down the road. It would vary with the side force of your turn - tighter faster turn means more difference between actual travel and the theorhetical path the tire should take. Having a larger slip-angle on the back end of your car leads to an oversteer effect that can be disastrous in a Jaguar or Maserati. Only a nutcase would try cornering their sports car with radials on the front, and bias ply on the back. I think there are states that address it in their motor vehicle laws.

But with the motorhome, you have twice the tires in back, so the slip-angle-effect wouldnt be very large back there anyway. One or two people on the site have said they did this and their rv handled fine. One of the folks was compelled to it because he couldn't get bias ply tires when he needed them.

I wont advise you, but would like to hear your experience if you do put radials up there. I presume you wont be trying to slide through any corners.

denison

[Jupp318]

Sent: 6/3/2003 6:40 PM

Denison,

In the UK Radials on front with cross ply on the rear is illegal.  Although I found this out after the fact,  The fact being that I put the cross ply's on the rear one lunchtime at work.  On leaving work I made it less than 100 yards and spun the car at about 15mph.  I took the car back to the car park and swapped the tyres back before continuing home!.  I do accept that there are double the amount tyres on the rear of our lovely wagons, but I would recommend asking the professionals before taking a risk.  Getting a 2.5 ton wagon sideways could seriously damage some of our hard-to-find rims if nothing else.

Ian

[denisondc]

Sent: 6/3/2003 7:51 PM

Driving on the level, while not towing anything - the RV might seem to handle all right. I would wonder though, with radials up front and bias ply in the back, about how it would handle while towing something, and especially while coming downhill in the mountains with a car in tow? This is something Ive never done in my winnebago. denison 

[melyash]

Sent: 6/4/2003 12:57 AM

In California it is ilegal to mix them. On any vehicle, and if found, the vehicle will be towed. You will not be allowed to continue even to the next gas station. They consider it that dangerous.

Matt

[Boat Nut]

Sent: 6/4/2003 3:04 AM

Yes, I did mix radials & bias plys back in the early 80s. I'm thinking the rule was radials in the back & bias ply up front. If I'm correct & that is how it was, they didn't give any problem. However it really handled much better when the following year I added the other radials.

Chuck (73 Brave)

[Beatty1950]

From Beatty1950
Sent: 9/2/2003 12:09 AM

I have a 1975 D19 with 318 engine, 44000 miles and 17.5" wheels.

When I purchase her on 8/1/2003 (so 1 month old today), she had 2 new radials on the front and 4 new Bias-Ply tires on the rear.  I have heard that mixing Radials and Bias-Ply is a bad idea.  I just returned from my second 250 mile weekend trip.  The D19 does seems sensitive to road changes and does not feel stable above 45mph.  Are the mis-matched tires the reason ??

[Lefty]

From: leftyizme
Sent: 9/2/2003 12:30 AM

You are exactly on target with your problem. mixing radials with bias-ply tires can cause many handling problems because they react to the road differently and at different reaction speeds. at least  you have the radials in the front, it would be a lot worse if the bias-ply were on the front.

--lefty

[Beatty1950]

From: Beatty1950
Sent: 3/15/2005 10:42 AM

My understanding is the Radial tire grip the road better than bias ply tire.  I noticed this fact when going from different road surfaces (Asphalt to Concrete or visa versa).  Especially around a corner.  I also understand that some states will not alow the mix of bias and radial tires.

I would check with some tire stores and other RVer for a better explaination ...

Remember it is a jungle out there.   Safety first...

Dave Beatty
Prior owner of the amazing 75 D19 Brave
Missing MissTank already and she just left yesterday

[VistaCruzr]

From: VistaCruzr
Sent: 3/15/2005 8:07 PM

Just a quick add to the Radial & Bias Mix questions. Mixing is never recomended by any dealer or shop. Handling will suffer no matter how you mixem. Radials on the front and bias ply on the rear are an extra dangerous combination. This will become odvious (and too late) in the event that you need to make a quick evasive action or lose control. This combination also feels like your front end is way loose. Matching the tires first may save time and expense on any front end troubleshooting.

[Cooneytoones]

From: cooneytunes
Sent: 3/15/2005 8:42 PM

In my opinion, and I will never mix bias & radials....but if you must mix, here is some good advice from Goodyear....

Should I "mix" tire types on my vehicle?

Tires of different size designations, constructions, and stages of wear may affect vehicle handling and stability. For best all-around performance, it is recommended that all tires be of the same size, construction (radial,non-radial) and speed rating. If tires of different speed ratings are mounted on a vehicle, the same size, type and speed ratings need to be placed on the same axle, the
tires with the lower speed rating will be the determining factor for permissible tire related vehicle speed. Never mix radial and bias-ply tires on the same axle. Get specific information from your Goodyear retailer. 



When buying just two new tires, should they be put on the front or rear?


When radial tires are used with bias or bias belted tires on the same vehicle, the radials must always be placed on the rear axle.
Never mix radial and bias-ply tires on the same axle. When you select a pair of replacement tires in the same size and construction as those on the vehicle, it is recommend you put them on the rear axle. A single new tire should be paired on the rear axle with the tire having the most tread depth of the others. On duals not more than 1 I/2 inches using the larger (newer) tire on the outside. But it's better to replace both at the same time.



Where can I find old production or discontinued tires for my classic or restored vehicle?


Recently discontinued tires are quickly consolidated and sold in large quantities to several sources and Goodyear would have no method of tracking the inventory after this sale.

Much older tires such as the older bias ply tires can many times be found through Kelsey Tire, Inc. in Camdenton MO. They have obtained the molds
for several of these older bias ply tires. They can be reached at (314) 346-2506. For more information you can call (800) 325-0091. Another source may be Coker Tire in Chattanooga, TN. They can be reached at (800) 251-6336.

Timmy

[legomybago]

I've had to do this when i was young and broke!! Still broke!!! Bias on the rear and radials on front makes a rig "crabwalk" while cruising, and when you hit any grooves in the road.....the radials tend to "over-look" them, but the bias ply tires on the rear will head right for them!! Not a good combo in my book. I had to warn my buddys when they barrowed the old pickup