Ask the Mechanic

Tire Size vs. Tire Price

(Steve Thompson)

READER: The front tires on my tractor seem to wear very quickly. I have changed the front tires twice, and the back tires are the original tires that came on the tractor. Do you have any ideas why my front tires wear so fast?

STEVE: When replacing tires on an MFWD (mechanical front-wheel drive) tractor, size is more important than price. If your front and rear tires are not the size of the tires that came on the tractor, any change in height will change the rate of movement the front and rear tires must have to keep your drivetrain in range. If the front tires and rear tires are not in range of each other, this can take your driveline out and cause premature tire wear. There is so much torque in a tractor driveline that the front drive and the rear drive must work as a team. Now, you know why when you change tire height on your vehicle, the speedometer has to be programmed to that tire size, otherwise it will not display the mph properly. Taller tires, of course, will make your speedometer read slower than you are really going. You can try that excuse out on a state trooper.

MORE TIRE TALK

STEVE: When replacing tires on an MFWD tractor, size is more important than price. Ag tires are hard to find these days, so be prepared to spend a little more time finding tires that match the size that came on the tractor. If your front and rear tires are not the size of the tires that came on the tractor, the rear wheels can be forced to be pushed. This arrangement will take your driveline out. There is too much torque going on in a tractor driveline that the front drive and the rear drive must work as a team.

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-- Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email mechanic@progressivefarmer.com, and be sure to include your phone number.

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