Tyre size 315/30 R21
Find 315/30 R21 Tyres
Free guidance for 315/30 R21 tyres. Performance SUVs and supercars. Always confirm fitment on your tyre sidewall.
Tyre Size Checker
Enter a UK tyre size such as 205/55 R16 91V to decode the width, profile, rim, load index and speed rating.
Find your tyre size on the sidewall, the driver's door frame, fuel flap or vehicle handbook.
- This tyre size may be incomplete. A full tyre size often looks like 205/55 R16 91V. Check your tyre sidewall for the load index and speed rating.
What 315/30 R21 means
315 is the section width in millimetres. 30 is the profile (sidewall height as a percentage of the width). R is radial construction. 21 is the wheel rim diameter in inches.
A full tyre size also includes a load index and speed rating, e.g. 315/30 R21 91V. The load index maps to a maximum weight per tyre, and the speed rating maps to a maximum speed at full load.
Where 315/30 R21 is commonly fitted
Performance SUVs and supercars.
Even when a tyre size is common, the specific tyre that's right for your vehicle depends on the load index, speed rating, and sometimes whether the original equipment is run-flat or EV-rated. Always confirm with your tyre sidewall, vehicle handbook or a qualified UK tyre fitter before fitting.
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You can find this on your tyre sidewall.
This tyre size may be incomplete. A full tyre size often looks like 205/55 R16 91V. Check your tyre sidewall for the load index and speed rating.
Step 1 of 7 — Start
What to check before fitting
- Confirm the size on your tyre sidewall
- Match or exceed the original load index and speed rating
- Check the EU tyre label for wet grip, fuel and noise
- Pick the right type — summer, all-season or winter
- Fit as a full set or at least a matched pair on the same axle
Frequently asked questions
Quick answers about UK tyre fitment, MOT rules and seasonal options.
315/30 R21 has a very low profile — is it run-flat?
Some, but not all, 315/30 R21 fitments are run-flat. Run-flat versions show "RFT", "ROF", "ZP", "EMT" or similar markings on the sidewall. Stick with run-flats only if your car was supplied with them and has tyre pressure monitoring.
Are 21-inch tyres harder to live with on UK roads?
21-inch and larger tyres tend to ride firmer, transmit more pothole impact and wear faster than 17"-18" sizes. On a UK B-road, premium-brand tyres in this size are often worth the extra cost.
Is 315/30 R21 a low-profile tyre?
Yes — a profile of 30 means the sidewall is only 30% of the tread width, which is short. Low-profile tyres handle precisely but transmit more road noise and are more vulnerable to potholes than higher-profile sizes.
Can 315/30 R21 tyres be repaired after a puncture?
Standard 315/30 R21 tyres can usually be repaired if the puncture is in the central tread area, smaller than 6mm and not on the sidewall. Run-flat versions of the same size often cannot be repaired.
Is 315/30 R21 available as a winter tyre?
Most UK fitments — including 315/30 R21 — are produced as winter tyres by Continental, Michelin, Bridgestone, Pirelli, Goodyear and others. Winter tyres are stamped with the 3PMSF symbol and stay flexible below 7°C.
Tyre sizes related to 315/30 R21
Same rim, similar width or profile — common alternatives UK drivers compare with 315/30 R21.
Tyre Finder UK provides general tyre guidance only. We do not guarantee tyre fitment, local stock, prices or fitting availability. Always confirm your tyre size, load rating, speed rating and vehicle requirements using your current tyre sidewall, vehicle handbook, manufacturer guidance or a qualified tyre fitter before fitting.