Tire size
225/40R18 Tires
On a 225/40R18 tire, 225 is the section width in millimetres. 40 is the aspect ratio: the sidewall stands 40% of that width, or 90 mm tall. The R means radial construction. 18 is the wheel diameter in inches — 457 mm. Add two sidewalls to that rim and the tire measures about 637 mm across, or 25.1 inches.
- In stock
- 76 brands
- From
- $114.99per tire · set of four $459.96
- 3PMSF certified
- 1 of 7Québec winter mandate, Dec 1 – Mar 15
- Load index
- 88–92560–630 kg
- Speed rating
- V · W240–270 km/h
- Overall diameter
- 637 mm25.1 inches
7 tires in stock in 225/40R18
Prices are per tire and already include the tire recycling fee. A set of four starts at $459.96 — delivery is free anywhere in Canada over $500 before tax.
225/40R18 — frequently asked questions
What do the numbers in 225/40R18 mean?
On a 225/40R18 tire, 225 is the section width in millimetres. 40 is the aspect ratio: the sidewall stands 40% of that width, or 90 mm tall. The R means radial construction. 18 is the wheel diameter in inches — 457 mm. Add two sidewalls to that rim and the tire measures about 637 mm across, or 25.1 inches.
How else is 225/40R18 written?
225/40R18 is also written 225 40 18, 2254018 or 225-40-18, and on a P-metric sidewall as P225/40R18. Some high-performance fitments stamp it 225/40ZR18 — the ZR there is a speed-rating marking, not a different size. All of them describe the same section width, aspect ratio and rim diameter, and any of them typed into our search lands on this page.
Which load index and speed rating should I pick for 225/40R18?
The 225/40R18 tires we have in stock run load index 88–92 (560–630 kg) with speed rating V, W (240–270 km/h). Match or beat the two figures on your vehicle's tire placard — usually on the driver's door jamb, sometimes inside the fuel filler flap. Going below the placard's load index or speed rating is unsafe; going above it is fine.
Can I fit a different size instead of 225/40R18?
Stay with the size on your placard unless a tire professional has signed off on an alternative. A workable substitute keeps the overall diameter within roughly 3% of 637 mm, carries at least the same load index and speed rating, suits the rim width you actually have, and clears the suspension and bodywork at full lock. Speedometer, odometer, ABS and stability control all calibrate off rolling diameter, so this is not a swap to make from a chart alone.
Are 225/40R18 tires legal for winter in Québec?
Québec requires winter tires from 1 December to 15 March. The tire has to carry the three-peak mountain snowflake (3PMSF) pictograph or be studded — an M+S marking on its own does not comply, and fines run $200 to $300. Exactly one of the 225/40R18 tires in stock here is 3PMSF-certified, and it carries a snowflake badge on its card above. British Columbia's rules run 1 October to 30 April on designated highways and accept either 3PMSF or M+S.
Do you install the tires?
No. We are delivery only — your 225/40R18 tires ship to your door anywhere in Canada, and we do not mount, balance or install. Take them to any shop, or fit them yourself.
Do I have to buy four?
No. Prices on this page are per tire, and the button on each card adds a set of four because that is the usual replacement. Order whatever quantity you need. If you are replacing only two, fit them on the same axle so grip stays balanced side to side.
Fitment guidance here is general. Your vehicle's tire placard and owner's manual are the authority, and a tire professional should confirm anything that departs from them.