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Difference Between a Radial, Bias, and Bias Belted Tire

Tech Question of the Week

Posted By Layla
6/10/2010 8:54:41 PM


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Types of tire constructions:

Radial tire has a ply that is at or near 90 degrees to the direction of travel and the ply goes from bead to bead. Bias ply tire has the ply(s) cut at an angle and the plies are laid over each other in a criss cross method

Bias belt tire has a ply cut at an angle and the belt is wrapped around the circumference of the tire over the bias ply or radial ply

Zero degree belt is laid at 90 degrees to the direction of travel over the other plies

tire construction1

tire construction12

Benefit of a radial tire (if your bike can work with a radial construction tire) is :
1) a better, more compliant contact patch
2) better transitioning response over bias
3) not as forgiving as the taller profile bias
4) Low aspect ratio - better grip but at max adhesion they slide more quickly with less warning
5) low profile looks great on many bikes

Criteria for running radials
1) Suspension of bike must be stiff enough to work with radial tires
2) wheel width must be wide enough to work properly for radial application
3) never run a radial front and bias rear

--Sukoshi Fahey (Ms.)
Sales Manager, North America


Reader Comments

Interesting since new indian Chieftain runs radial on back and bias on front. They said it was ok to run Michelin Commander II on back but it hit and didn't feel great.

They replaced it but made another mistake. They were out of radials and put the same Dunlap series three but it had a b which I assume is bias vs radial.

Seems to ride and handle good but they are ordering the radial which us OEM. The OEM radial on back got flat across the middle at 11,500 miles with some edge cupping.

I wonder if it is better to not put radial back on. Comments? Is it just best to stick to OEM size and tire.

Keith marvin
Palm coast, FL
Saturday, October 17, 2015
Editor Response I would like to look into this. I just rode an Indian home. I asked American Biker to take the whitewalls off and replace them with blackwalls. I don't know if they switched out the makes or models. I'll check.

The bike handled like a dream. I've never ridden a bike so stable. I'll report back on the tires.
Not mixing radial and bias applies to the same axle. It is possible to mix on a car that has two wheels per axle.

On a 2-wheel motorcycle you can't mix radial and bias as there are only one wheel per axle. Therefore it is ok to put a bias on the front and a radial on the back of a 2-wheel bike. Myself and about 5 thousand (that I know of) can attest to this.

Edgewater, FL, FL
Friday, January 23, 2015
Editor Response Not sure I understand?
My bike came stock with bias ply tires and been replacing them quite often. Can I put a bias belted tire in the rear and a bias ply in the front or is that not recommended?

Jameson Simonelli
Hingham, MA
Tuesday, March 18, 2014
Editor Response It would be helpful to know what bike he is on. In general yes you can run the following combinations:

Front Rear
Radial Radial (if it is an approved fitment by the Mfr or a custom bike)
Bias Radial (most often this is a custom fitment, a few OE bikes like BMW F650 have this combo)
Bias Bias
Bias Bias Belted (you should never run belted front and bias rear)

Also on some bikes that came with bias ply tires front and rear it is possible to upgrade to the radial fitment for the set. Bike needs rigid enough frame and wide enough wheels.

A bias belted tire is generally used on heavier touring bikes or bikes that need to have a belted construction. The belt helps prevent the tire from growing at speed thus maintaining a better contact patch. Bigger contact means the load is spread over a wider area which helps give a better mileage in turn.

Hope this helps.

Avon Tyres

We have a very helpful tire presentation from Avon. I will try to publish it next week for a greater understanding of tire technology.--Bandit

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