Free tool
Do I need tires yet?
Every tire shop on earth will tell you the answer is yes. This one checks the two things that decide it — how much tread is left and how old the rubber is — and tells you plainly if the answer is no.
No sign-up and no contact details asked for. If your tires are fine the page says so and stops. No countdown, no pitch.
Step one
How much tread is left?
Three ways in, depending on what you have to hand. Check three spots across each tire and use the shallowest reading — tires rarely wear evenly, and the worn edge is the one that decides.
A pin-style gauge reads in 32nds straight off the barrel. Sit the shoulders of the gauge flat on the tread blocks and push the pin to the bottom of a main groove — not into a sipe, and not on top of a wear bar, both of which will read shallow.
Some gauges read in millimetres. Divide the millimetre reading by 0.79 to get 32nds — 4 mm is almost exactly 5/32".
Tread wear indicators are short raised bars molded across the bottom of the main grooves, every few inches around the tire. Look for the small triangle, TWI mark or brand logo on the shoulder — it points at the nearest one.
Your reading
Tread depth
Usable life left
Measured against the 2/32" legal limit, not against zero. The last 2/32" is not yours to use.
This only changes the percentage, never the verdict. Most passenger tires leave the factory at 10–11/32"; truck and winter tires start deeper, so pick the closest match or a new winter tire will read under 100%.
Step two
How old is the rubber?
Tread wears; rubber ages on its own schedule. The DOT code stamped on the sidewall is the only honest answer to how old a tire is — the day you bought it is not the day it was built.
Paste the whole serial if it is easier — only the last four digits carry the date. The first two are the week, the last two are the year: 3421 is the 34th week of 2021.
Where to find it
- Look on the sidewall for the letters DOT, followed by a run of letters and numbers. It is molded in, the same colour as the tire, so it is easier to feel than to see.
- This is where everyone gets stuck: the full code with the date on the end is normally only stamped on one side of the tire. If the side facing you ends after the plant and size codes, the date is on the inboard face — look from under the car, or turn the wheel to full lock to see the inside of a front tire.
- Four digits inside a small oval, right at the end. Three digits instead of four means the tire was built before 2000.
Age check
Type the four digits and this will tell you the week the tire was built, how old it is now, and what that means.
That is not a date code this page can decode. It needs four digits where the first two are a week from 01 to 53 — so 0624 works and 6024 cannot, because there is no 60th week. Check you have the last four digits of the DOT serial rather than the load index or the size.
Three digits means the tire was built before 2000, when the code did not carry a decade. Which year stopped mattering a long time ago: that tire is at least twenty-five years old and belongs off the car whatever the tread looks like — including if it is the spare that has never touched the road.
Built
Age today
In whole years, rounded down.
Six and ten years are manufacturer guidance, not law — no US state puts an age limit on a passenger tire. Rubber ages whether the tire is driven or parked, which is why a spare with full tread can still be past it, and heat and sun move it along faster than a garage does.
The answer
So — do you need tires?
Questions
The things people ask next
Short answers, including the ones that mean you do not need to buy anything.
How often should I actually check?
Once a month, at the same time you check pressures, and again before any long drive. It takes under a minute per tire. Check three spots across each tire — outer shoulder, middle, inner shoulder — because a tire rarely wears evenly, and the shallowest reading is the one that counts.
Does the spare count?
Yes, and it is the one nobody checks. A full-size spare ages in the trunk at the same rate as the four doing the work, so a spare with beautiful tread can still be a ten-year-old tire. Check its date code and its pressure twice a year. A temporary compact spare is a different animal: it carries its own speed and distance limits printed on the sidewall, usually 50 mph and a short trip to a shop.
What does uneven wear tell me?
Worn down the centre with the shoulders still full means over-inflation — the tire is crowned and riding on its middle. Worn on both shoulders with the centre full means the opposite: chronic under-inflation. Worn on one shoulder only is alignment, usually camber or toe, and no new tire will survive it until the alignment is fixed. Patchy or scalloped wear that you can feel with your palm points at worn shocks, struts or a wheel that is out of balance.
The tread is fine. Does age really matter?
It does, and this is the part the tread check cannot see. Rubber cures and hardens over time whether the tire is driven or parked, which is why a barely-used spare or a low-mileage car on original tires can be past it with most of the tread still there. Six years is the usual point at which manufacturers ask for a yearly inspection, and ten years is the usual hard stop — but both are manufacturer guidance, not law. Heat and sunlight, which South Florida has in quantity, move it along faster.
Is 2/32" really the legal line?
In most US states, yes — it is the point at which a tire is legally worn out, and it is what the penny test finds. A handful of states word it differently or set the bar elsewhere, so treat 2/32" as the floor rather than the whole answer. Either way, well before that, wet braking has already fallen off sharply: below 4/32" the grooves can no longer move enough water out of the way.
Do I have to replace all four?
Not always. On a front- or rear-wheel-drive car, two is fine if the other two still have real tread — and the new pair goes on the rear axle regardless of which end drives, because a car that loses grip at the back first is much harder to catch. All-wheel drive is stricter: many manufacturers require all four within a small difference in circumference, so a single replacement on a worn set can cook a differential. Check the owner's manual before buying one tire.