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Tire Size Calculator

Built by Kevin Glover · @gloverbuilds · Verified formula

Compare tire sizes. Calculate diameter, circumference, and speedometer difference. Free tire calculator.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

In this article

How to Use This Calculator
Tips for Best Results

Comparaison

Le diamètre total doit rester à ±3% de l'original. Des pneus plus grands : le compteur indique moins que la vitesse réelle. Plus petits : il indique plus. Un changement de 3% = erreur de 2 km/h à 100 km/h.

Plus-Sizing

En augmentant le diamètre de jante, diminuez le profil. 195/65R15 → 225/45R17 : diamètre total change de 1% (acceptable). Plus large = meilleure adhérence mais plus de consommation.

⚡ CalcWolf Insight

Consumer Reports found that at 4/32 inch tread remaining (halfway worn), wet braking distance increases 30%. At 2/32 inch (legal minimum), stopping distance nearly doubles vs new tires.

Frequently asked questions

Puis-je changer de taille ?▾

Oui, dans ±3% de diamètre total. Au-delà : compteur faussé, ABS perturbé.

Quand remplacer ?▾

À 1,6 mm de profondeur (minimum légal en France). À 3 mm : distance de freinage sur mouillé augmente de 30%.

✓ Math logic verified against primary sources → See our verification process

Kevin Glover · @gloverbuilds

Founder, CalcWolf · GLVTS · Blickr

All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →