Guidelines for Tire Size Mixing, Tire Construction Mixing, Tire Tread Design
Mixing, New Tire Installation, and Tire Rotation of Auto and Light Truck Tires

To maintain the designed handling and traction capabilities of a vehicle it is critical to select and
install tires of the correct size, construction, and tread design on the proper wheel position.  The
same attention to correct size, construction, tread design, and wheel position must be considered
when rotating and servicing tires.
 
Follow the vehicle manufacturer’s recommendations for tire selection, application, and service. 
The vehicle manufacturer recommendations can usually be found in the vehicle owner’s manual, 
on the tire information placard or vehicle certification label. Never choose a replacement tire of a
smaller tire size with less load carrying capacity than the OE tire size at the specified vehicle
placard pressure. In the absence of vehicle manufacturer recommendations follow the guidelines
below to help assure the tire fitment provides optimum vehicle handling and traction.
 
New Tire Application Guidelines
• When radials are used with bias or bias belted tires on the same vehicle, the radials must
always be placed on the rear axle.
• Never mix radial and bias ply tires on the same axle.
• When you select a pair of replacement tires of the same size and construction as those on
the vehicle, we recommend you place them on the rear axle.
• A single new tire should be paired on the rear axle with the tire having the most tread of
the other three.
 
Rotation Guidelines
• Rotate tires as recommended in Product Service Bulletin # 2005-30 dated 11/23/2005.
• When rotating a full size spare, place the spare on the right rear wheel position.
• Never place a temporary spare into a rotation pattern.
 
Winter Tire Guidelines
• It is recommended that snow tires be applied to all four wheel positions.
• If winter tires are installed on the front axle of any vehicle, they must also be installed on
the rear axle.
• If studded tires are installed, they must be applied to all four wheel positions.
• Never apply non-radial snow tires on the rear axle if radial tires are on the front axle
unless the vehicle is equipped with duals on the rear axle.
• Always apply four winter tires including studded winter tires on police pursuit vehicles.
 
4WD and AWD Guidelines
Always check and follow the recommendation in the vehicle owner’s manual, even small
variances in outside diameter may cause drive-train damage or mechanical malfunction. If no
instructions for tire mixing appear in the vehicle owner’s manual follow these guidelines:
• Do not mix sizes.
• Do not mix radial and bias-ply constructions.
• Do not mix tread patterns such as all-season and all-terrain.
 
Guideline for Speed Rated Tires
• If tires with different speed-ratings are installed on a vehicle, they should be installed
with like pairs on the same axle.  The speed-capability will become that of the lowest
speed rated tires. It is recommended that the lower speed-rated tires be placed on the front
axle regardless of which axle is driven to help prevent potential oversteer.
• For tires installed on Law Enforcement or Emergency Vehicles refer to PSB 2005-28.
 
Please cover this information with your sales and service staff to assure they have the knowledge
to sell and service tires so that your customer’s vehicles provide the good handling and traction
needed for a safe driving experience.