Even after we've inspected a tire twice in our warehouse, we still recommend a quick five-minute inspection at the mount shop before they put it on your wheel. Here's what to check.
Step 1 — Confirm the size and DOT date
Match the sidewall to your invoice. Size string, brand, model — all four characters and numbers. The DOT date code at the end should match what you were quoted. If anything is off, stop and call the seller before mounting.
Step 2 — Re-measure tread depth
Borrow the mount tech's depth gauge and measure tread in three places across the face of the tire — outer shoulder, center, inner shoulder. They should all be within 1/32 of each other and within 1/32 of the seller's stated depth.
Step 3 — Check both sidewalls under bright light
Mount shops have bright overhead lights — use them. Look at both the inner and outer sidewalls for any cuts, scrapes, or bulges. The inner sidewall is the one you couldn't see in online photos, so it's the one that occasionally surprises people. If there's any bulge or bubble, do not mount.
Step 4 — Run your hand across the tread face
You're feeling for:
- Cupping — a wavy wear pattern, usually caused by worn shocks on the previous vehicle
- Feathering — tread blocks worn into a sawtooth pattern, caused by toe misalignment
- Embedded objects — gravel, glass, the occasional nail that didn't fully puncture
Step 5 — Look inside the tire for repair patches
Ask the mount tech to show you the inside of the tire before they mount it. A properly placed inner patch — a mushroom-shaped plug-and-patch in the tread face — is fine and adds nothing to the failure risk. A patch in the shoulder, two patches close to each other, or any patch on the sidewall is a no-go.
Step 6 — Watch the balance numbers
Once the tire is mounted and on the balancer, watch the weight reading. A well-built used tire balances with less than 1.5 ounces of weight on either side. A tire that needs more than 3 ounces probably has a shifted belt — refuse it.
Five minutes at the mount bay is the difference between a tire you'll forget about for 40,000 miles and a return shipment.