Free tools · Manufacturer data · No signup
Compare wheels & tires like an engineer
Bolt patterns, fitment specs, tire-size math, and side-by-side comparisons — based on manufacturer data. No fluff, no guesswork.
1,000+ size pairings · 550+ bolt patterns · UK & US pricing
Tire Size Calculator
Convert sizes, see overall diameter change, sidewall, and speedometer error. Plus-sizing made easy.
OpenBolt Pattern Database
Bolt pattern, hub bore, and thread pitch for popular cars — by make, model, and year.
OpenFitment Guides
Per-vehicle stock specs, bolt pattern, and plus-1/plus-2 sizing that keeps your speedo honest.
OpenTire Brands
Real tire lines from Michelin, Continental, Bridgestone and more — by season and segment, with price comparison.
OpenWhy CompareWheels
Most wheel and tire sites are either thin affiliate stores or marketing pages dressed up as guides. We build the opposite: data first, opinions second. Every fitment row has a source, every wheel spec is traced to a manufacturer page or industry database, and the calculators are pure formulas you can verify with a calculator and a ruler.
Frequently asked questions
- What does tire size comparison show?
- A tire size comparison shows the difference in overall diameter, section width, sidewall height, and speedometer error between two tire sizes. For example, comparing 205/55R16 vs 225/45R17 reveals a 1.2% diameter change and a 4 km/h speedo offset at 100 km/h.
- Can I replace my tires with a different size?
- Yes, but the overall diameter should stay within ±3% of the original to avoid speedometer error and clearance issues. Use a tire size comparison tool to check the diameter difference before switching.
- How do I compare wheel sizes?
- Enter both tire sizes (e.g. 195/65R15 and 205/60R15) into a tire size comparison tool. It will calculate the change in diameter, sidewall height, and rolling circumference so you can see if the swap is safe.
- What is plus-sizing for wheels?
- Plus-sizing means fitting a larger-diameter wheel (e.g. going from 15" to 16") while using a lower-profile tire to keep the overall diameter the same. CompareWheels shows you the exact tire width and aspect ratio needed for each plus-size step.