Can you mix tires? When to replace 2 or 4

Jump to: Replace four when you can · Replacing two · Replacing one · Mixing brands · Mixing sizes · AWD and 4WD · Buy checklist

Short answer: the US Tire Manufacturers Association (USTMA) recommends replacing all four tires at once when you can. If you replace only two, match the size, load index and speed rating on the door placard, and put the new pair on the rear axle, not the drive axle alone. Mixing brands or models is discouraged. On AWD and 4WD, keep rolling diameters closely matched or you can stress the drivetrain.

Replace four when you can

USTMA’s replacing tires page says replacing all four at the same time is best for performance. A matched set keeps grip, braking feel and electronic aids more consistent left to right and front to rear. Toyo’s selection bulletin says the same idea in practice: unless the vehicle maker specifies otherwise, all road tires should share the same size, type and speed rating, and you should not mix different speed ratings on the vehicle.

Start from your door placard. Confirm size, then make sure the load index and speed rating meet or exceed the original. For how worn is too worn, see when to replace tires and tread depth.

Replacing two tires

Budget sometimes means a pair, not a full set. USTMA’s rules for replacing fewer than four:

• Match the vehicle maker’s size, load index and speed rating.
• Install the two new tires on the rear axle.

Why the rear? Newer tires clear water better. USTMA says greater rear traction helps avoid hydroplaning and an oversteer slide that can cost vehicle stability. BFGoodrich (and Michelin guidance quoted on that page) makes the same point: deeper tread on the rear reduces the chance of a fishtail in the wet, and rear traction loss is harder to recover from than front traction loss. Put the new pair on the rear even on a front wheel drive car.

After the install, keep rotating on schedule so wear stays even. See our tire rotation patterns guide.

Replacing one tire

USTMA warns that replacing a single tire can negatively affect suspension, transmission and treadwear. BFGoodrich adds that a lone new tire next to three worn ones changes rolling circumference, which hurts handling and can damage AWD drivetrains. If one tire must be replaced alone:

• Pair the new tire with the tire that has the deepest remaining tread (USTMA says include a matching full size spare when choosing that partner).
• Install that matched pair on the rear axle.

If the other three are already near the wear bars, replacing a pair or all four is usually the safer path. Have a licensed installer measure tread and advise.

Mixing brands and models

BFGoodrich says mixing different brands is not recommended. Compounds, tread patterns and construction differ, so braking and cornering responses can differ when you need them most. If you must mix for cost:

• Keep a matched pair on each axle (same brand and model left and right).
• Put the newer or deeper pair on the rear.
• Do not mix radial tires with bias ply tires. All four must share the same construction.

Toyo separately advises against mixing different speed ratings on any vehicle.

Mixing tire sizes

Tires on the same axle must be the same size. Mixing sizes front to rear is only appropriate when the vehicle shipped with a staggered fitment from the factory. Otherwise use one size all around, taken from the placard. You can compare a proposed size change with our tire size comparison calculator, and still confirm load, speed rating, rim width and clearance with an installer.

AWD and 4WD special care

All wheel and four wheel drive systems often rely on all four tires having nearly the same rolling diameter. Toyo’s bulletin says 4WD and AWD need closely matched diameters to avoid strain on differentials or viscous couplings, and that inflation must follow the placard because pressure also changes circumference. BFGoodrich says that if the owner’s manual gives no mixing instructions, do not mix sizes on those vehicles at all.

Many AWD makers publish a maximum tread depth difference across the set (sometimes only a few 32nds of an inch). Check your owner’s manual before replacing two on an AWD vehicle; some require all four.

Winter tires are always four

Toyo says winter tires should always be fitted in matched sets of four. Fitting only two winter tires on the drive axle can create a large grip mismatch. Details on when to switch and why four matter are in our winter tires guide.

Buy and install checklist

1. Copy size, load index, speed rating and cold PSI from the door placard.
2. Prefer four matching tires. If buying two, plan them for the rear axle.
3. Match construction (radial with radial). Avoid mixing brands when you can.
4. On AWD or 4WD, confirm the maker’s tread depth difference limit before buying only two.
5. Have a licensed installer mount, balance and torque the wheels, then set cold placard pressures and handle any TPMS relearn.

Informational only, not professional or safety advice. Your vehicle maker’s manual and a licensed installer take priority over this page.