Primary keyword: replace all four tyres. Secondary: replace two tyres or four, AWD tyre replacement, new tyres front or rear, tyre replacement cost.

Do you really need to replace all four tyres at once?

For a normal front- or rear-wheel-drive car, no. If two tyres are worn and two still have plenty of tread, you can replace just the worn pair. What matters is that the two tyres on the same axle match each other in make, model, size and roughly in wear. Replacing all four at once is tidier and keeps grip even, but it isn’t a mechanical must on a 2WD car.

All-wheel drive changes the answer, and that’s where the real cost decision lives.

If I only replace two, where do the new tyres go?

On the rear axle — even on a front-wheel-drive car. It feels backwards, but the deeper tread belongs at the back. Rear tyres losing grip first causes oversteer, where the back steps out and the car can spin, which is far harder to catch than the front washing wide. Tyre makers including Michelin fit the newer pair to the rear for exactly this reason. Your fitter should do this automatically; if they offer to put them on the front, ask why. This is also why you can’t freely mix worn and new across an axle — see mixing tyre sizes front and rear.

Why is AWD different?

An all-wheel-drive system sends power to all four wheels through differentials and, on many cars, a centre coupling. Those parts assume every tyre is turning at almost the same speed. A tyre with less tread has a slightly smaller rolling diameter and spins fractionally faster, and the driveline has to absorb that difference constantly. Fit two fresh tyres against two worn ones and you can cook the centre coupling or diff — a repair that can dwarf the price of tyres.

That’s why AWD makers specify a maximum tread-depth difference between tyres, often just a couple of millimetres. We cover the number that protects your driveline in tread depth tolerance on AWD vehicles, and the whole question in do AWD cars really need all four tyres replaced together. If your remaining tyres are within tolerance you may replace two; if not, you’re up for four.

What does it cost either way?

Here’s the illustrative cost reality (2026 guide figures — confirm with your retailer).

The short-term saving of buying two is real, but on an out-of-tolerance AWD it can turn into a four-figure driveline bill. On a 2WD car, buying two is genuinely cheaper with no downside beyond slightly uneven wear timing.

Can I make a worn AWD tyre match?

Sometimes. Some tyre shops can “shave” a new tyre down to match the tread depth of your existing set, letting you replace one or two without breaching tolerance. It’s a niche service, costs money, and only makes sense when the other tyres are still fairly fresh. For most people, if the set is well worn it’s cheaper overall to replace all four and reset the clock — then rotate them regularly so they wear together and you face the same bill only once. Buying a good matched set and looking after it usually beats rotating cheap tyres, and it keeps your cost per kilometre down.

What about staggered and performance setups?

Cars with different front and rear tyre sizes (staggered fitments) can’t be rotated front-to-back, so pairs wear at different rates and you’ll often replace an axle at a time by design. High-performance and heavily loaded vehicles also chew tyres unevenly. In both cases, match within each axle and follow the handbook.

Bottom line: On a 2WD car, replacing two matched tyres and putting them on the rear is fine and cheaper. On an AWD, check the tread-depth tolerance first — buying two out-of-tolerance tyres can cost you a driveline, which makes four the cheaper option.

Frequently asked questions

Is it bad to replace only two tyres?

Not on a 2WD car, as long as the pair matches and goes on the rear. On AWD it can be bad if the tread-depth difference exceeds the maker’s tolerance.

Why do new tyres go on the back, not the front?

Deeper tread at the rear keeps the back of the car planted in the wet. Losing rear grip causes a hard-to-control spin, so the newer, grippier pair belongs at the rear regardless of which wheels are driven.

How do I know my AWD’s tread tolerance?

Check the owner’s handbook or ask the dealer — it’s often expressed as a maximum millimetre or percentage difference between tyres. When you can’t confirm it, replacing all four is the safe default.

Does replacing all four at once save money long term?

It can, because a matched set rotated regularly wears evenly and you buy once instead of staggering purchases. On AWD it also removes the risk of driveline damage from mismatched tread.

Sources: Michelin Australia — Can you mix different tyres?; Les Schwab — Replacing tyres on AWD vehicles. Costs are a 2026 guide; confirm with your retailer and owner’s handbook.