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When can you change just one tyre?
You can change just one tyre when the one on the same axle is recent, lightly worn and compatible: same size, same construction and same type (summer, winter or all-season), ideally the same model.
This is typically the case with an unrepairable puncture on an almost new tyre. If, on the other hand, the remaining tyre already has much less tread, fitting a single new tyre creates a difference in grip between the two sides of the axle.
Why are they usually changed in pairs?
They are usually changed in pairs because two tyres with different wear, model or compound on the same axle can behave differently under braking, when cornering and in the wet.
- Braking: the car may tend to pull towards the side with more grip.
- Wet roads: the more worn tyre drains water less well (see aquaplaning).
- Electronics: ABS, stability control and indirect TPMS work better with matching wheels.
What must match on the same axle?
On the same axle, tyres must have the same size and the same construction, and should ideally be of the same type, with model and wear as similar as possible.
| Feature | On the same axle |
|---|---|
| Size (e.g. 205/55 R16) | Identical, among the approved sizes |
| Load index and speed rating | In line with the registration document |
| Type (summer, winter, all-season) | Identical |
| Brand and model | Recommended to be identical |
| Tread depth | As similar as possible |
If you are not sure how to read this information, see how to read your tyre size.
Should new tyres go on the front or the rear?
Many tyre manufacturers recommend fitting the two new (or less worn) tyres on the rear axle, even on front-wheel-drive cars.
The reason is stability: if the rear loses grip in the wet, the back of the car tends to slide out, a situation that is harder to control than a front end that runs wide. Vehicles with different front and rear sizes are an exception, as each tyre stays on its own axle: always follow the manufacturer's guidance.
What changes with four-wheel drive?
With four-wheel drive, differences in rolling diameter between the wheels can put strain on the transmission, which is why some manufacturers require all four tyres to be replaced together, or only very small differences in wear.
The rules vary from model to model: before replacing one or two tyres on a 4x4 or on many SUVs, check the owner's manual.
An unrepairable tyre in Milan: what should you do?
If the tyre cannot be repaired after a puncture, in the short term you can fit the spare wheel or space-saver and then decide calmly whether to replace one or two tyres. To understand when a tyre can be repaired, read when a tyre can be repaired.
In Milan and its province, SOS Tyre comes out 24/7, in 30 minutes on average, for a wheel change wherever the vehicle is; in an emergency, supplying a new tyre is arranged on the phone depending on size and availability, while a planned replacement can be booked as a tyre change at your home. Call +39 377 326 0999.
Frequently asked questions
Can I fit two different brands on the same axle?
It is not advisable. Even in the same size, tyres from different brands or models can have compounds and tread patterns with different grip, especially in the wet. On the same axle it is best to have the same model; between the front and rear axles a difference is more acceptable.
Can I keep the space-saver on until I buy a new tyre?
Only for as long as strictly necessary. The space-saver is a temporary spare, with a maximum speed shown on it, typically 80 km/h, and a limited range. Replace it with a normal wheel as soon as possible and read the guide on how far you can drive on a space-saver.
Is a summer tyre and a winter tyre on the same axle OK?
No. Summer and winter tyres have compounds and tread patterns designed for different conditions and, on the same axle, would behave differently under braking and when cornering. Also, where the winter requirement applies in Italy, you need winter tyres on all wheels or chains on board.
Does the TPMS need resetting after changing a tyre?
With indirect TPMS, normally yes, after bringing all the wheels to the correct pressure. With direct TPMS it depends on the vehicle and on whether the sensor was removed or replaced. You will find details on the sensors in the guide on TPMS sensors.