While it’s always best to replace a vehicle’s tires as a complete set, accident damage, road hazards and economic constraints can make it necessary to replace them individually as well. However, mixing tire brands, tire models or even significantly different tread depths can challenge a vehicle’s drivability. Therefore how many tires are going to be replaced influences both the best replacement tire choice, as well as where they should be installed on the vehicle.
Front-wheel or rear-wheel drive: Front-wheel drive and rear-wheel drive vehicles will normally wear the tires on their driving axle at a faster rate than their non-driving axle. This is especially true of front-wheel drive vehicles that can wear out front tires two to three times faster than rear tires. When replacing tires as a pair, the best practice is to match the existing tire brand, line, size and specifications.
All-wheel-drive and four-wheel drive: Because many all-wheel-drive and four-wheel drive powertrains mechanically link all of the vehicle’s tires together, mismatched tire tread depths can create unwanted driveline stresses.
Tread wear gradually reduces every tire’s overall and rolling circumferences, so tire revolutions per mile (tire RPM) will increase as treads wear down. Since most new tires feature 10/32” to 12/32” beginning tread depth, their circumferences will decrease about 1 ½” during their lifetime. The tire revolutions per mile (RPM) listed in the manufacturers specifications are for new tires.
Therefore for many all-wheel-drive and four-wheel drive powertrains, in addition to matching the tire brand, line, size and specifications, it is also necessary to maintain equivalent tread depth at all wheel positions to eliminate unwanted driveline friction, wear and possible failure. This subject is often addressed in the vehicle owner’s manual or a manufacturer Technical Service Bulletin (TSB).
In order to prevent mismatching tire RPMs, it requires either replacing all four tires or by shaving the tread of the replacement tire(s) to the same tread depth as the other tires that will remain on the vehicle.
Replacing One Tire: Untimely road hazards or traffic accidents may require replacement of just one tire. When this happens, the best practice is to replace the damaged tire with one that is an identical match of the tire brand, line, size and specifications. This will help retain equivalent tire traction and vehicle handling characteristics.
Assuming all of the vehicle’s tires are of the same size and regardless of the original vehicle position the tire being replaced was from, the industry recommendation is to install the new tire opposite the deepest treaded of the original tires and place them both on the rear axle.
However this may not be possible if a high-performance rear-wheel drive vehicle is equipped with staggered tire sizes (larger tires on the vehicle’s rear axle vs. its front axle), tires that feature a directional tread design or a combination of both. In these cases, an exact replacement tire should be selected and installed in the position dictated by the original location of the tire being removed from service. If this would result in significantly different tread depths side-to-side or front-to-rear, pairs or complete sets of new tires may need to be installed.
Replacing Two Tires: Vehicle misalignment and inadequate tire rotations are the most common reasons pairs of tires will need to be replaced. When this happens, the best practice is to replace the pair of worn tires with a pair that is an identical match of the tire brand, line, size and specifications. This will help maintain tire traction and vehicle handling characteristics.
If that’s not possible, the next-best option is to install a pair of tires that are the same type (summer, all-season, all-terrain or winter, etc.) and feature the same basic tire specifications (size, load capacity and speed rating). This will help retain equivalent tire traction and vehicle handling characteristics.
When replacing only two tires, the industry recommends installing the new tires on the rear axle and placing the partially worn existing tires on the front axle to reduce the possibility of an oversteer condition causing the vehicle to spinout on wet or snow-covered roads.
Replacing Three Tires: it is not common to replace three tires unless a vehicle has been in an accident. The other possible exception is for light truck vehicles originally equipped with a full-size spare tire and wheel that matches those originally on the road. Light truck vehicle spare tires and wheels are generally carried in or under the truck bed, or hung off of its tailgate, Unfortunately this constantly exposes them to temperature extremes, direct sunlight and harsh chemicals. After years of inactivity, previously unused spare tires subjected to these types of long-term exposure should be replaced. They should NOT be installed on the vehicle for ongoing service.
Replacing Four tires: maintaining tire inflation pressures, vehicle alignment settings and performing periodic tire rotations* will typically result in all of the vehicle’s tires equally sharing the work and sharing the wear throughout their life.
In addition to delivering predictable performance, consistent comfort and return on their investment, this will also permit drivers the freedom to select a set of replacement tires that offer the latest technology to meet their anticipated driving conditions and financial considerations.
The best practice is to replace all tires on the vehicle at the same time with a set that matches the vehicle’s original size dimensions, load capacity and speed capabilities.
There is no reason to gamble with replacement tire selection, because four-of-a-kind always beats two pairs!
- Routine tire rotations, typically at 5,000- to 7,500-mile increments, will allow tires to wear more evenly and provide equivalent tread life. Follow industry recommended rotation patterns and/or guidelines spelled out in the vehicle’s owner’s manual.