About the Tire Tread Life Calculator
This tire tread life calculator estimates how many miles your tires have left. Enter the tread depth the tires had when new, the depth you measure today (in 32nds of an inch, as tread gauges in the US read), the miles you have driven on them and the depth at which you plan to replace them. It works out your actual wear rate, the remaining miles, the total life you can expect from the set and how many months that is at your yearly mileage.
Use it when budgeting for a new set, deciding whether tires will last through winter or a long road trip, or checking whether your real wear matches the manufacturer’s treadwear warranty. Measure in several grooves across each tire and use the lowest reading; uneven wear between the inside and outside edges points to an alignment or pressure problem.
Most US states set a legal minimum of 2/32 inch, which is where the built-in wear bars become flush with the tread. Many tire experts recommend replacing at 4/32 inch because wet and snow traction fall sharply in the last few 32nds. The estimate assumes your future driving wears the tires at the same rate as up to now.
With the default inputs, the estimated miles remaining is 12,500 mi. Change any value above to recalculate instantly.
How to use the tire tread life calculator
- 1Find the new tread depth on the tire maker’s spec sheet or your purchase invoice.
- 2Measure the current depth with a tread gauge in several grooves and use the lowest reading.
- 3Enter the miles driven since the tires were installed.
- 4Choose your replacement depth and yearly mileage.
- 5Read the miles and months remaining and the expected total life.
Formula and method
The calculator measures how many miles it has taken to wear away each 1/32 inch of tread so far, then multiplies that rate by the 32nds you have left above your chosen replacement depth. Total life adds the miles already driven, and months remaining divides the remaining miles by your yearly mileage.
Usable tread used compares the tread lost so far with the usable tread between new and the replacement depth. Wear is roughly linear for most tires, but aggressive driving, low pressure, poor alignment, heavy loads and hot climates accelerate it, and tires should also be replaced on age regardless of tread. 1/32 inch = 0.79375 mm.
- New depth
- Original tread depth in 32nds of an inch
- Current depth
- Lowest measured groove depth now
- Replacement depth
- Depth at which you will replace (2/32–4/32 in)
Worked examples
10/32 new, 6/32 now after 25,000 miles
Losing 4/32 in over 25,000 miles is 6,250 miles per 32nd. With 2/32 left above the 4/32 replacement point, the tires have about 12,500 miles left — roughly 12.5 months at 12,000 miles a year — for a total life of 37,500 miles.
Truck tires: 15/32 new, 9/32 at 30,000 miles, replace at 2/32
Six 32nds worn in 30,000 miles is 5,000 miles per 32nd. Running to 2/32 leaves 7/32, or 35,000 miles — about 28 months at 15,000 miles a year.
Fast wear on a performance tire
Four 32nds gone in 14,000 miles is just 3,500 miles per 32nd. Only 1/32 remains above 4/32, so expect about 3,500 more miles — 80% of the usable tread is already used.
Frequently asked questions
How do I know how many miles are left on my tires?+
Measure the tread depth, subtract it from the new depth to get the 32nds worn, and divide the miles driven by that to get miles per 32nd. Multiply by the 32nds left above your replacement depth (usually 2/32 or 4/32 inch).
What tread depth is legal?+
Most US states require at least 2/32 inch of tread, which is when the molded wear bars across the tread become flush with the surface. A few states have different rules and many other countries use 1.6 mm (about 2/32 inch). Check your state’s vehicle code.
Why replace tires at 4/32 inch?+
Tests by tire makers and consumer groups have shown wet braking distances grow significantly as tread falls below about 4/32 inch, because shallow grooves cannot clear water. Replacing at 4/32 (or 5/32–6/32 for snow) keeps much more wet and winter grip.
How do I measure tread depth without a gauge?+
The penny test is a rough guide: insert a penny head-first into a groove; if you can see all of Lincoln’s head, you have 2/32 inch or less. A quarter shows about 4/32 inch at Washington’s head. A cheap tread gauge is far more accurate.
How long do tires last on average?+
Many all-season passenger tires are designed for roughly 40,000–70,000 miles, while summer performance tires may last 20,000–30,000. Regardless of tread, most makers recommend inspecting tires after about 6 years and replacing them by around 10 years of age.