Bias vs Radial
 

Classic Car Tires 101 | AUTOMOTIVE MILEPOSTS

In a nutshell, the article states a radial has more flex.

If we lower tire pressure, we get more flex, more heat and less mileage.

If we raise tire pressure, we get less flex, less heat and greater mileage.

So, what say ye? Have we been duped into believing radials are better, like having to change oil every 3000 miles, and running door placard pressures, ET doesn't exist, etc....

I think motorcycle and to a lesser extent bicycle tires have rotten Crr due to being bias not radial.

I for one don't feel in any way "duped" when driving on or buying radial tires.
Should you ever have the pleasure of driving an American circa mid-50s or
earlier car, you will be horrified at how tenuous the bias ply tire's connection
with the road was "back in the day." Although the radial tire was invented in
the mid-40s, it wasn't widely used in the USA until the 60s. Even in the late
60s, OEM radial tires were a major part of muscle car advertising copy.

Most every 'Net site that discussses the differences between bias and
radial ply tires comes up with comparisons like this:

There are two types of tires mostly used in cars and commercial vehicles:
Radial and Bias.

Bias Ply tire: This type of tire has diagonal or bias plies. These plies
crisscross. This makes tire strong in all directions because of the plies
overlap.

Radial ply tire: In a radial tire, the ply cords run in the radial direction.
The plies run parallel to each other and vertical to the tire bead. Stabilizer
belts are applied over the plies to give extra strength parallel to beads.

Now we look at advantages of radial tire over a bias tire:
1. Good high speed capacity
2. Longer lasting and Longer tread life (Up to30%- 50% longer)
3. Steel Belted - Results in tougher overall construction
4. Better floatation ,larger contact area wider footprint
5. Low heat build-up or run cooler
6. Lower rolling resistance
7. Better Fuel Economy
8. Better stability
9. Wear resistant
10. Smoother, more quiet ride

Disadvantage of radial tire over a bias tire:
1. More prone to puncturing at side walls
2. Side wall bulging
3. More difficult to repair
4. Higher purchase price
5. Heavier steering at low speeds but power steering facility is
there so it is acceptable.
Read more: What is the difference between bias and radial tires

Here is link for the more visual learner. Granted, it is Michelin discussing
their agricultural tires, but the visuals work just as well for road tires:
Michelin AG - Advantages - Bias vs Radial

Tires for trailers, ATVs, motorcycles, and classic cars are special cases and
require vehicle specific research.

In 1972, I bought a 1966, VW MicroBus and one of the first changes was to replace all four, cross-bias tires with radials. On the way home, I took a familiar, high-speed turn and nearly rolled it . . . the radials where that much better than the cross-bias tires. Steering had changed from a guessing game to a precise art.

Bob Wilson

My Aunt bought a 1966 Cadillac new and it wore out the factory bias ply tires in 6000 miles. She replaced them with Michelin X tires and drove it on them until it had 70,000 miles. She replaced them because they were 13 years old and dry rotting, not worn out.

You couldn't get me to drive a car on bias play tires. I even put radials on my 37 Ford, and promptly lost a hubcap going around a turn a little too fast.

regards
Mech

Radial tires create less heat when flexing because the plies are perpendicular to the road at point of contact. Bias ply tires have plies that are perpendicular to each other and at 45 degree angles to the road at point of contact. The plies fight each other when flexing which creates heat and accelerates wear. Since the sidewall plies in the radial tire are not fighting each other there is much less heat created.

regards
Mech

The link makes a number of statements which in my (somewhat educated) opinion are just flat wrong. For instance
Now it seems obvious to me that the tire's sidewall isn't supporting the car's weight. That's being supported by the pressure of the air in the tire - otherwise, we'd never get flats :-)

I had an International Scout II that came with bias tires. I thought the steering was worn out; driving it on the highway was like steering a boat, I had to target distant landmarks to keep it straight, and turning had to be planned well in advance. I replaced the tires with radials, and it was a new vehicle. It steered precisely and straight.

In my humble opinion, BIAS TIRES SUCK!

As above, if you were ever on these tires in the rain, you'd never, ever, choose to have them in place of radials.

I can say without doubt, that my new bias tires on my motorcycle coast almost double what the radials would. Huge difference not only coasting, but in feel/feedback of what the tires are doing.

I have always preferred bias on bikes. I tried radials a couple of times now and like the bias better.