Tire causing pull?

[gfh77665]

I understand a front tire can be structurally sound and have plenty of tread depth, but cause a pull. If a car pulls right, does this probably mean the right tire is causing it? Would a rotation to the rear essentially eliminate it?

(Please don't suggest I buy new tires, I am helping someone else, the car is not mine).

Thanks.

 

[bradepb]

If all front end parts are good and alignment correct, try rotating to rear. A tire can do all kinds of stuff and look good to the eye.

 

[sasilverbullet]

Yes, definitely. To know for sure, you can swap the tires right to left and see if the pull changes. If it does, then you can get the tire/wheel "Hunter Road Force" balanced. This will identify for sure. Then replace the tire, voila, your done.

 

[eljefino]

Nah, could be either tire. It doesn't know what rim it's supposed to be on, and it's supposed to roll straight. So if it pulls to a side it pushes, too.

 

[Planb]

I have this problem also. If I put the bad tire on the driver's side I get pull to that side.(front) If I put that tire on the passager side no more pull. Just change the location of the tire and see what happens.

 

[mclasser]

I didn't know "radial pull" was a thing until experiencing it with new tires once. After an alignment, the car pulled right. Went back and complained and they swapped the front tires. Car now pulled left. Had the defective tire replaced under warranty and that fixed the issue.

 

[CapriRacer]

Every tire has a property called conicity - root word cone. It is the amount of force pushing sideways. It can be positive or negative or zero.

A pull is caused when the difference between the two front tires exceeds the vehicle's threshold - and every vehicle is different.

Let's assume you have a vehicle that is sensitive to a value of 10 (arbitrary units!!) - and you have front tires of +7 and +10. The difference is 3, so no pull. But if I change to tires with a value of +7 and -7, the difference is 14 = a pull.

I hope it is obvious that it isn't large values that causes pulls - just the difference.

 

[JetStar]

Had a brand new 1988 Escort GT pull to one side badly, from day one. Turned out to be a bad Eagle GT tire.

 

[Planb]

Originally Posted By: CapriRacer
Every tire has a property called conicity - root word cone. It is the amount of force pushing sideways. It can be positive or negative or zero.

A pull is caused when the difference between the two front tires exceeds the vehicle's threshold - and every vehicle is different.

Let's assume you have a vehicle that is sensitive to a value of 10 (arbitrary units!!) - and you have front tires of +7 and +10. The difference is 3, so no pull. But if I change to tires with a value of +7 and -7, the difference is 14 = a pull.

I hope it is obvious that it isn't large values that causes pulls - just the difference.


Nice explanation. Thank you.

So what actually causes the push sideways. I am going to assume a slight difference in diameter from inside to outside?

 

[Planb]

I should also ask, the concity of the tire is it more of a structure issue of how the tire was assembled? Or more rubber? Both?

 

[CapriRacer]

Originally Posted By: Planb


Nice explanation. Thank you.

So what actually causes the push sideways. I am going to assume a slight difference in diameter from inside to outside?


Centering of the belts and side to side variation in tread thickness.

That means you can wear conicity into a tire.

 

[jjjxlr8]

Besides conicity, there is also "pull" which is designed into tires which is intended to counteract the crown of the roads. It's sometimes referred to as PRAT (Ply steer Residual Aligning Torque). Tread pattern and tire construction are the primary drivers of PRAT.

 

[CapriRacer]

Originally Posted By: jjjxlr8
Besides conicity, there is also "pull" which is designed into tires which is intended to counteract the crown of the roads. It's sometimes referred to as PRAT (Ply steer Residual Aligning Torque). Tread pattern and tire construction are the primary drivers of PRAT.


True,but the effect on the vehicle is quite different. Prat causes the whole vehicle to drift slowly,but evenly and that is corrected by a slight bit of sterling input-close to imperceptible and nothing to worry about compared to conicity.

 

[Lubener]

"Usually" a car will pull towards the bad tire. Rotating will confirm.Brakes could also be dragging on one side. I had a vehicle with a bad tie rod pull when torgue was applied during acceleration but was fine coasting. Further investigation probably is needed.

 

[gfh77665]

Originally Posted By: Planb
I have this problem also. If I put the bad tire on the driver's side I get pull to that side.(front) If I put that tire on the passager side no more pull. Just change the location of the tire and see what happens.


UPDATE: Thats what I did, and it fixed it. The offending tire was on the right front. I balanced and rotated the front two, and it immediately solved the pulling. (due to tread style, we left the back tires alone).

Thank you all for your help.

 

[CapriRacer]

Just an FYI:

Pulls are not a case of a bad tire. They are about a tire that is significantly different than its mate for conicity.

I hope everyone understands that when one takes a look at a population of tires (say a thousand of them - all otherwise identical), you can plot the various parameters and you should get a bell curve (proper name = Gaussian distribution!). That means most of the population is around the center (in this case Conicity = Zero!), but the further you get from the center, the fewer individuals you will have. In this case, chances are that replacing the one tire will result in a tire with a lower value - and there is a possibility that the replacement tire could have a large value.