Tire Proration & Warranty Calculator
Estimate remaining tread life, prorated warranty credit, and betterment — by tread depth or mileage warranty.
Quick Answer
A tire with 6/32" remaining out of 10/32" new has about 60% usable tread life left. At a purchase price of $180, that's roughly $108 in warranty credit — and $72 in betterment already consumed. For mileage warranties, a 50,000-mile tire with 20,000 miles driven has 60% remaining, worth $108 on a $180 tire.
| Scenario | Result |
|---|---|
| 50,000-mi tire · 20,000 mi used · retail $180 | 60% remaining · warranty credit: $108 |
| 60,000-mi tire · 45,000 mi used · retail $200 | 25% remaining · warranty credit: $50 |
| Tire with 5mm tread (new = 8mm) | 62.5% remaining · credit: 62.5% of purchase price |
| 6/32" remaining from 10/32" new | ~60% remaining · credit: ~60% of purchase price |
Most tire warranties subtract the legal minimum (2/32") before calculating usable life — tread at or below that threshold has no warranty value.
New all-season tires often start around 10/32" (≈ 8 mm); winter and truck tires may be deeper.
Measure at the lowest point across the tread for safety and warranty decisions.
Many regions use 1.6 mm as the legal minimum; tread at or below this is treated as worn out.
Use your original purchase price or the current replacement price, depending on how your warranty or insurer calculates credit.
Usable Tread Remaining
45.3%
Based on usable tread above the minimum (1.6mm), matching many tread-based warranty and protection formulas.
Original
8mm
Current
4.5mm
Usable Remaining
2.9mm
Total Usable Tread
6.4mm
Tread depth is above both the legal minimum and typical “replace soon” thresholds. Continue normal use but monitor wear and age regularly.
Tread Depth Reference
Depth thresholds based on common safety and legal guidance for passenger tires.
| Depth (mm) | Approx 32nds | Status | Recommended Action |
|---|---|---|---|
| 8.0+ | 10+/32" | New / Excellent | Normal use |
| 6.0–8.0 | 7–10/32" | Good | Normal use; monitor wear |
| 4.0–6.0 | 5–7/32" | Fair | Monitor closely; plan ahead for replacement |
| 3.0–4.0 | 4–5/32" | Low (Replace Soon) | Wet traction declining; schedule replacement, especially before bad weather |
| 1.6–3.0 | 2–4/32" | Very Low | High risk in wet/snow; replace as soon as possible |
| ≤ 1.6 | ≤ 2/32" | Legal Minimum / Bald | Do not drive; immediate replacement required |
Get a plain-English explanation of your results — what they mean for your vehicle and driving experience.
Prorated Tire Value Examples (Original Price $160, Min Tread 2/32")
| Original Tread | Current Tread | % Usable Remaining | Prorated Credit | Betterment (You Pay) |
|---|---|---|---|---|
| 10/32" | 8/32" | 75% | $120 | $40 |
| 10/32" | 6/32" | 50% | $80 | $80 |
| 10/32" | 4/32" | 25% | $40 | $120 |
| 10/32" | 2/32" | 0% | $0 | $160 |
Assumes original tread 10/32", minimum 2/32", and original price $160. Actual warranty credits may be based on current selling price and brand-specific terms.
Formula & Explanation
- Minimum tread is subtracted — tread below 2/32" has no warranty value in most programs
- Price basis choice matters — some warranties use purchase price; others use current selling price
- Mileage warranty formula — unused % = (warranty miles − miles driven) ÷ warranty miles × 100
How to Use This Calculator
- 1Enter the original purchase price: Input the price paid per tire (or current replacement cost) — used to calculate prorated credit and betterment.
- 2Enter original tread depth: Input the tread depth when new. Most passenger all-season tires start around 9/32"–11/32" (7–9mm); winter and truck tires may be deeper.
- 3Enter current tread depth: Measure at the lowest point across the tread — this is what warranty programs and insurers use for coverage calculations.
- 4Adjust minimum tread depth if needed: The default is 2/32" (1.6mm), the legal minimum in many regions. Change it if your warranty uses a different threshold.
- 5Review the results: Read the remaining usable percentage, prorated credit, and betterment amount. Switch to Mileage-based mode for mileage-warranty estimates.