Putting the wrong tyre size on your car can affect safety, handling, and even your speedometer. Here's how to always get the right size every time.
Finding the Correct Tyre Size for Your Vehicle
The easiest and most reliable way to find the correct tyre size for your car is to check the placard inside your driver's door, in the fuel filler flap, or in the owner's manual. This tells you the exact tyre specification recommended by the manufacturer. You can also read the size directly from the sidewall of one of your existing tyres — the size code is clearly moulded into the rubber and consists of width, aspect ratio, construction type, rim diameter, load index, and speed rating (for example, 205/55 R16 91V).
If you enter your vehicle registration number into Just Mobile Tyres' booking system, it will automatically identify compatible tyre sizes for your vehicle, taking the guesswork out of the process entirely. This is the fastest and most accurate method for most customers. For vehicles with different front and rear tyre sizes (common on performance cars and SUVs), make sure you specify which axle needs new tyres when booking.
Can You Fit a Different Size Tyre?
Fitting a tyre slightly different from the manufacturer's specification is sometimes possible, but comes with important caveats. Changing tyre width or aspect ratio affects the overall rolling diameter of the tyre, which alters speedometer and odometer readings. A tyre that is too wide may rub against wheel arch components. Changes to the load index or speed rating can invalidate your vehicle's type approval and your insurance.
Unless you have specific reasons for wanting a different size — such as fitting winter tyres on a narrower wheel — we always recommend fitting the manufacturer-specified tyre size. If you are uncertain, just call Just Mobile Tyres on 07855 123 711 and our team will confirm the correct specification for your vehicle before ordering anything.
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