Why Change Tyres in Pairs

It is not. Mixing brands, tread patterns or tread depths on one axle is legal in the UK. What is illegal is mixing construction types – a radial alongside a cross-ply – under regulation 26. Legal and advisable are different things, though: matched pairs brake and corner more predictably, particularly in the wet.

Yes, and in that situation it is the sensible choice. If the tyre remaining on that axle has 5mm or more of tread and you can obtain the same brand, model, size, load index and speed rating, one tyre is perfectly reasonable. The awkward cases are older cars where the original model has been discontinued.

Side does not matter in the way axle does – there is no rule about nearside or offside. What matters is that the pair on that axle is as closely matched as possible, and that the axle carrying the deeper tread overall is the rear one. If a single new tyre would leave the rear axle weaker than the front, the fitter may move wheels around to correct that.

Because of how a car behaves when grip finally runs out. Worn rears let go before worn fronts do, and a rear that lets go first produces oversteer – a spin most drivers cannot catch. Understeer from the front is far easier to recover. Keeping the better tread at the back is the safer failure mode, whichever wheels are driven.

The common trade guideline is that a difference of more than about 2mm to 3mm across an axle is too much. Some vehicle manufacturers specify tighter limits, and four-wheel-drive vehicles are stricter again. If in doubt, measure both tyres in three places and compare the lowest readings rather than the best ones.

Only for specific reasons. Different sizes on one axle will fail, as will mixed construction types or any tyre below 1.6mm. Different brands or tread patterns alone will not fail the test, though a tester may record an advisory. An advisory is worth acting on rather than filing away for next year.

Frequently, yes. All-wheel-drive systems are sensitive to differences in rolling circumference between wheels, and a worn tyre alongside a new one is read as continuous slip. That can damage the centre differential or coupling over time. Check the handbook – many state a maximum permitted tread difference across the vehicle.

You should not. Run-flats have reinforced sidewalls and a quite different stiffness to conventional tyres, so pairing the two on one axle gives inconsistent handling and braking. If your car came with run-flats, replace them with run-flats in pairs unless you are converting the whole vehicle to conventional tyres and carrying a spare wheel.

They are a poor idea. You cannot see internal damage, verify the age, or know whether the tyre has been run flat or kerbed hard. Matching tread depth on the surface tells you nothing about the casing beneath it. Given tyres are the only thing connecting the car to the road, a new matched pair is money far better spent.

Mismatched tyres that remain legal will not usually invalidate a policy on their own. Illegal tyres are a different matter – if a tyre is below 1.6mm or fitted contrary to the construction rules, an insurer may argue the vehicle was not roadworthy following a claim. Keeping tyres legal and matched removes the argument entirely.

Yes – that is exactly what we do. Our vans carry the stock, the balancer and the torque equipment, so a matched pair can be fitted on your driveway or in a workplace car park while you carry on with the day. Give us the size from the sidewall or the registration and we will confirm availability before the van sets off.