Are my old tires safe to drive? Not if they are 10 years old, and not if the tread is at or below 4/32 inch — even if they look fine. Rubber ages from heat and air whether a tire is used or not. Check the DOT date code and measure the tread, or run Servik's predict_risk tool.
It's a worrying question, and it's worth asking plainly: a tire can look fine and still be done. Rubber ages through oxidation and heat even when a tire is unused, including spares, and tread wears away long before the legal minimum in most states. Servik's predict_risk tool weighs age and tread together and returns an advisory risk band: low, elevated, or high. The bands are guidance-grade, not calibrated probabilities — there are no outcome labels to calibrate them against — so read high as "replace now," not as a percentage chance of failure. It is advisory only: never a diagnosis, never a guarantee. Run it from /tools or /chat.
Maybe not. Tread is only half the story — age is the other half. Read the four-digit date code at the end of the DOT code on the sidewall: the first two digits are the week, the last two are the year. DOT 3515 means week 35 of 2015. A tire made in week 35 of 2015 is 11.2 years old, past the 10-year manufacturer maximum from Michelin and Bridgestone.
Use a tread-depth gauge — under $10 and the only method that tracks wear over time — or the quarter test: if tread does not reach Washington's head, you are at or below the 4/32 inch safer point. The penny test marks the 2/32 inch legal minimum: if you can see all of Lincoln's head, the tire is worn out.
Give the tool the tire's age in years and the tread depth, from /tools or /chat. It returns a risk band with its drivers and its uncertainty, so you can see exactly which signals drove the verdict.
For a tire with dot_age_years 11 and tread_depth_32nds 3, the tool returns risk_band "high", with band_status "guidance_grade_not_calibrated". The drivers are tread_at_safer_replace_point and age_at_or_past_replace_guidance, and the uncertainty is noted as high because mileage-versus-life inputs were missing. The advisory is decisive: "Both replace signals are present — the tire is past the 10-year replace guidance AND at or below the 4/32 inch safer replace point — so replacement is the guidance here, not continued driving. This is advisory, not a guarantee." A separate tread check on the same 3/32 inch reading gives verdict replace_soon, with 1/32 inch left above the 2/32 inch legal minimum. This high verdict was re-checked and confirmed in Servik's round-2 bake-off: two replace-grade signals mean replace now.
High means both replace signals are present. Do not treat it as a warning to watch the tire — treat it as the replacement guidance it is. Get quotes through /get-quotes or in /chat and call a local tire shop to confirm it stocks your size.
Thin inputs fall back to guidance with no band. If the tool cannot place a band, give it more: mileage, whether a warning light is on, whether maintenance is overdue, and whether the tire is mismatched to the season. More real inputs make a more useful band — never a guessed one.
Servik publishes no tire price, so a replacement set is priced by the shop's quote — Servik is still collecting accurate price data for tires. What delaying costs is an inspection failure and a safety risk: where states require a safety inspection, the inspection fee itself is commonly $12–$30, and a tire at or below 2/32 inch tread fails in most states. A tire at 3/32 inch is already below the safer 4/32 inch point, so budget for replacement now rather than after a failed inspection.
Call a local tire shop now when the band is high, when the tire is 10 years or older whatever the tread looks like, when tread is at or below 4/32 inch before rain or snow driving, or when you see sidewall cracking, bulges, or a cut. Age damage is invisible from the tread alone, so a shop inspection — not a photo — is what confirms it.
Not if they are 10 years old or past it, and not if the tread is at or below 4/32 inch — even if they look fine. Check the DOT date code and measure the tread, or run predict_risk from /tools or /chat and let it weigh both signals together.
No. The bands are guidance-grade, not calibrated probabilities: there are no outcome labels to calibrate them against. High means two replace-grade signals are present — age past the 10-year guidance and tread at or below the 4/32 inch safer point — so replacement is the guidance. It is advisory, never a diagnosis or a guarantee.
Not necessarily. Rubber ages through oxidation and heat even when a tire is unused, including spares. Manufacturer guidance from Michelin and Bridgestone says replace a tire at 10 years or more, even if it looks serviceable. Age is its own signal — check the DOT code, not just the tread.
One signal — old age or low tread alone — still points toward replacement, but the tool weighs them together, so give it both numbers. The worked example had both signals at once, which is why the band came back high with a decisive replacement advisory.
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