Replace 2 Tires or All 4? AWD Rules and Where New Tires Go
Last updated . Sources were opened on Oct 31, 2026, and are linked in the text.
When one tire is damaged or two are worn, the question is whether you can get away with replacing just those. Often you can. But all-wheel drive cars are pickier, and where the new tires go matters on every car. Here is what tire makers, retailers and Consumer Reports say.
Measure first: Tire Check takes a tread reading for each tire and, if you say the car is AWD, flags a gap of more than 2/32" between your highest and lowest reading. It runs in your browser, with no sign-up.
Check your tires with Tire Check
The short answer
- Four matching tires is the ideal. Michelin says if you replace only one, it should match the other three as closely as possible in brand, model, size and remaining tread (Michelin).
- If you replace two, put the new pair on the rear axle. Tire Rack says this applies to front-, rear- and all-wheel drive vehicles (Tire Rack). Michelin also says to fit a new pair on the rear axle (Michelin).
- On AWD and many 4WD vehicles, the tires also need closely matched tread depth or circumference. Check your owner's manual first.
Why new tires go on the back
Tires with less tread hydroplane in shallower water and at lower speeds. Tire Rack explains that if the front tires lose grip first, the car tends to keep going straight (understeer), which most drivers can recover from by easing off the gas. If the rear tires lose grip first, the back of the car can slide or spin (oversteer), which is much harder to control. So it puts new pairs on the rear axle, and it says small front-to-rear differences of up to 2/32" are fine and still allow rotation (Tire Rack).
Costco's tire centers have the same policy: the least worn tires go on the rear, whether you buy one tire or two (Costco tire center FAQ).
All-wheel drive: why matching matters
As a tire wears, it gets slightly smaller around, so a worn tire turns faster than a new one (Consumer Reports). AWD systems allow small, short-lived differences in wheel speed, such as in a turn. Tire Rack says that if mismatched tires force the differentials or couplings to work all the time, they can overheat and wear out early, and that mixing brands, tread designs and tread depths may cause driveline parts to fail (Tire Rack).
What the limits look like:
| Who | Guideline | Source |
|---|---|---|
| Tire Rack (general) | All four within 2/32" of tread depth, or within 1/4" in circumference | Tire Rack |
| Audi (as quoted by Tire Rack) | Rolling radius of all four the same, or within 4/32" of tread depth | Tire Rack |
| Subaru (as quoted by Tire Rack) | Circumference no more than 6 mm (1/4") apart | Tire Rack |
| Porsche Cayenne (as quoted by Tire Rack) | Within 30% of the remaining tread of the other tire on the same axle | Tire Rack |
Your own owner's manual is the final word. Consumer Reports notes that Subaru, for one, warns owners that mismatched circumferences can seriously damage the AWD system (Consumer Reports).
One flat tire on an AWD car
- Measure all four. Use a tread depth gauge in the grooves that have the wear bars (Consumer Reports).
- If the other three are nearly new, one matching new tire usually stays within tolerance (Tire Rack).
- If they're moderately worn, ask about shaving: a shop removes tread from a new tire so it matches the others. Tire Rack and Consumer Reports both put the price at Tire Rack at about $25 to $35 per tire (Tire Rack; Consumer Reports). Consumer Reports says shaving makes the most sense when the other tires are no more than about half worn, roughly 6/32", and that it will likely void the new tire's treadwear warranty. It also says the equipment isn't common, so not every shop can do it.
- If they're heavily worn, or wear is uneven, replacing all four is the safer choice (Tire Rack). Consumer Reports adds that uneven wear is a sign to buy four and have the suspension and alignment checked (Consumer Reports).
Two-wheel drive cars
Front- and rear-wheel drive cars don't have the AWD driveline issue, so replacing a pair is common. The rear-axle rule above still applies. Keep the size, speed rating and load index the same as the others unless your vehicle maker says otherwise (Consumer Reports).
Before you buy
- Read all four date codes too. A tire that matches on tread but is much older may need replacing anyway. See how to read the DOT date code.
- For the full set of replace-now signs, see Do I need new tires?
- Most of the rebates we list require a set of four. If you're replacing all four anyway, our current tire rebates table lists the current offers and their dates.
This guide is general information, not a substitute for advice from a tire professional or your vehicle maker.
Common questions
Do I have to replace all four tires on an AWD car?
Not always. Tire Rack's guideline is to keep all four within 2/32 inch of tread depth or 1/4 inch in circumference. If the other three are nearly new, one matching tire is usually fine. If they're more worn, a shaved new tire or a full set may be needed. Your owner's manual comes first.
If I only buy two new tires, do they go on the front or the back?
On the back. Tire Rack and Michelin both say a new pair goes on the rear axle. Tire Rack says this applies to front-, rear- and all-wheel drive cars, because rear tires that hydroplane first are harder to control.
What is tire shaving?
A shop removes tread from a new tire on a machine so it matches the depth of your other, partly worn tires. Tire Rack and Consumer Reports put Tire Rack's price at about $25 to $35 per tire, and Consumer Reports says it will likely void the tire's treadwear warranty.