Proper Matching

Paired tires should be of the same size designation, construction, and tread design and be as close as possible to same outside diameter. Mismatching duals forces the larger diameter tire to carry an overload, causing it to over-deflect and overheat. The smaller diameter tire, lacking proper road contact, wears faster and irregularly.

Note: Determine the actual difference in diameter by measuring the tires (with a steel tape) at least 24 hours after initial inflation. Matching should be done before installing tires on the vehicle. Applies only if tires are of the same tread.

Using the same tire size and construction that was specified as the original equipment for that vehicle will normally produce the best performance from the vehicle and the tires. However, there are times when mixing of different tire sizes and constructions on a vehicle is necessary. Some mixing of tires can be allowed if certain rules are followed:

• Never mix different tire sizes or construction types on the same axle.
• Bias ply tires can be mounted on steer axles and radial tires on single-axle drive positions of two-axle vehicles. Reversing these positions may result in handling problems. 
• Either bias ply or radial tires can be mounted on the steer axles if the vehicle has multiple drive axles. 
• All multiple-drive axles should have the same size and construction tires.
• Tires mounted on trailers may be bias or radial, as long as all tires on each individual axle are the same size and construction. 
• No mixing of tire sizes and constructions are allowed on four-wheel-drive type vehicles (4WD).