Vibration at 60-70 mph that goes away above 80 — tires or something else?

Speed-specific vibration that appears and disappears at certain speeds is classic wheel balance. Every imbalance has a "resonant speed" where it's worst. Below and above that speed, you won't feel it as much. Possible causes in order of likelihood: 1. **Wheel balance shifted** — weights can fall off, especially the stick-on kind. Re-balance all 4 ($60-80 at any tire shop). 2. **Tire defect** — a separated belt will cause vibration in a narrow speed range. Have the shop check for flat spots or bulges while balancing. 3. **Bent rim** — hit a pothole recently? They can check runout during the balance. 4. **Warped rotor** — if the vibration is worse when braking at those speeds, it's the rotors, not tires. CV joints typically cause vibration during turns or under hard acceleration, not at a specific road speed. Start with rebalancing — it solves this 80% of the time.

One thing people miss: make sure the hub surface was cleaned before mounting the new tires. A tiny bit of rust or debris between the hub and wheel throws off the balance no matter how well the tire is balanced on the machine. Ask the shop to clean the hub face if they rebalance.

If rebalancing doesn't fix it, ask for a "road force balance." Regular spin balancing doesn't catch tire defects — road force simulates the weight of the car on the tire and finds problems a regular balance can't. Worth the extra $20-30 per tire.