Tyre guide

How to check your tyre size before buying

Before comparing tyres, confirm the size on the current sidewall or vehicle placard. This guide explains what the numbers mean and why trims can differ.

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Last verified: 2026-06-12

Read the sidewall first

A tyre size such as 245/45 R18 tells you the width, profile and wheel diameter. The load index and speed rating after it also matter, so do not compare only the first three numbers.

Check the vehicle placard

Many cars were sold with more than one wheel option. The placard, handbook or current tyre sidewall is safer than assuming every trim uses the same size.

Match the season to your use

Summer, winter and all-season tyres suit different conditions. If the size fits but the season does not match how and where you drive, keep comparing.

Tyres to use as comparison examples

Available Econodrive AS 185/75 R16 104/102R All season

Dunlop · Van tyre · All season

Econodrive AS 185/75 R16 104/102R All season

from £111.06.

£111.06

Tyre sizes tracked: 185/75 R16 104/102R

Available Econodrive AS 195/60 R16 99/97T All season

Dunlop · Van tyre · All season

Econodrive AS 195/60 R16 99/97T All season

from £103.61.

£103.61

Tyre sizes tracked: 195/60 R16 99/97T

Available Econodrive AS 195/65 R16 104/102T All season

Dunlop · Van tyre · All season

Econodrive AS 195/65 R16 104/102T All season

from £114.84.

£114.84

Tyre sizes tracked: 195/65 R16 104/102T

Sources and last checked

Last checked 2026-06-12. This page uses retailer product information, comparable products and any cited public context available during the latest check. Use it as a shopping aid, then verify live price, delivery and stock with the retailer.

Firmness questions

Can the same car model use different tyre sizes?

Yes. Trim, wheel option and market can change tyre size, so confirm the size on your vehicle before ordering.

What does 245/45 R18 mean?

245 is the tyre width in millimetres, 45 is the profile, and R18 means the tyre fits an 18-inch wheel.

Can I fit a different tyre size?

Only use an alternative size if it is approved for your vehicle and wheel. When unsure, check the handbook or ask a qualified tyre fitter.