Welcome back to our informative post about the issue of mismatched tires. This time, we are going to have a closer look at duals.

Matching tire OD on duals

Of course, it is also very important to match tire OD/circumference on dual tire fitments. As with drive tire mismatching, the smaller tire needs to rotate faster than the larger tire to cover the same distance. We already know that the larger tire will have to carry a larger portion of the load.

This means that the larger tire will likely be overloaded. Not only will it suffer fatigue damage, but also have a much shorter tire life. The small tire, instead, is carrying a lighter load and is being turned too slowly to cover the same distance as the large tire. Therefore, the tread will be scrubbing and wear very quickly.

But that’s not all! As the tread wear progresses much faster on the lightly loaded smaller tire compared to the heavily loaded large tire, the difference in tire OD/circumference between the two duals grows at a more rapid pace.

In other words, this situation will destroy both tires in a very short time, as you can see from the picture on the right: four different tires are mounted on the rear axle of this haul truck, some are new, some are worn and tread patterns and brands are mismatched.

Your servicing dealer can help with recommendations for acceptable dual OD/circumference differences. You can find some helpful guidelines in the BKT OTR Tire Maintenance Manual.

How to avoid the cost of mismatching tires

Well, the most common issue leading to mismatched tire OD is when one tire must be removed for repair. That is why at BKT, we recommend a good tire management program. Keep an inventory of variously worn, repaired tires for replacement needs.

When a tire must be removed from service for repair, use care to replace it with a tire of the same design from the same manufacturer. Make sure it has a similar remaining tread depth to the other tires on the vehicle.

Loader Tolerances-Source: SAE J2204 Articulated Truck Tolerances

Please be aware that the recommended tolerances are general in nature and are not references to specific equipment or manufacturers. Consult your equipment manufacturer for best recommendations. And remember, all comments in this post refer to tires that are properly inflated for the loads applied.

Is there anything else you wish to know about mismatched tires? What are your experiences? Has there ever been a very big issue? Join in and let us know!