4x4 Clubhouse - Corrrect Mounting & Balancing

Tire Balancing

Tire out-of-balance is usually in the tread area (A), see illustration, since the tread is the heaviest part of the tire and the part farthest away from the center of the axle. In the illustration, (A) represents the heavy spot; in the example let's say it is 5 ounces. (B) is the area of the rim where weights are usually applied. (C) is the center of the axle, (D) is the diameter of the rim, (E) is the diameter of the tire and here we are using a 34 inch diameter tire for the example. Area (A) is 17 inches away from the center of the axle (a 34 inch diameter tire divided by 2 equals 17 inches) and area (B) is 7-1/2 inches away from the center of the axle (a 15 inch rim divided by 2 equals 7-1/2 inches).

In this illustration the 5 ounces of imbalance is far out from the center of the axle (17 inches) and an attempt to balance the assembly will require putting weights on the edge of the rim which is much closer to the center of the axle (7-1/2 inches). To balance the tire in this example by placing weights at point (B) to correct the 5 ounces of out-of-balance at point (A) will require considerably more than five ounces of weight to bring the tire into balance. These figures will change depending on the number of ounces of weight a tire is out of balance and the diameter of the tire in relation to the diameter of the rim it is mounted on. In this particular example the amount of weight required to bring this 5-ounce out of balance into balance with the tire mounted on a 15 inch diameter rim would be 10.6 ounces. The 'taller' a tire is and the 'shorter' the rim is the more weight it takes to bring the assembly into balance. Even more weight is required when using the stick-on type of weights applied to the drop center part of the wheel because the weight is being applied even closer to the axle. This is sort of like a 200 pound kid trying to seesaw with a 100 pound kid...it just does not work unless the heavier kid moves closer to the center of the board.

The best way to overcome this situation is if you were to determine the heavy spot of the tire (in the illustration it is 5 ounces) before it was mounted and place a 5 ounce internal 'balance patch' or 'dough compound' directly opposite the 5 ounce heavy spot by gluing the 'balance patch' to the inside of the tire which would be placing the 'balance patch' (weight) very close to the 17 inch radius from the center axle point it would require only about 5 ounces of 'balance patch' to properly balance the tire. After this would be done and the tire mounted on the wheel the entire tire and wheel assembly could be put on a balancing machine to correct for any imbalance in the wheel itself or some minor dynamic imbalance that may be present. None of these procedures will give satisfactory results if the rim is warped or has too much run-out to begin with.

We hope this information helps you in understanding some of the factors involved in proper balancing and that a tire is never 'out of balance' as much as the number of ounces of weight required to 'balance' it using conventional balancing equipment.

Disclaimer: As much as we would like to help, we cannot and will not give advice on fitting our tires to any particular vehicle. Ride height changes due to age and use do not allow for steadfast rules. Your local retailer may be able to help by inspecting your vehicle first hand.

Interco Tire Corp.
P.O. Box 6
Rayne, LA 70578-0006

Phone: 337-334-3814
Fax: 337-334-9796

Copyright  2001 Interco Tire Corp. All Rights Reserved.

www.intercotire.com