How to Use the Spare Tire Safe Distance Calculator
After a flat tire forces you onto a spare, how fast and how far you can safely drive depends heavily on which type you have. The temporary "donut" spare found in most trunks is narrower and smaller in diameter than a regular tire, which reduces grip and heat dissipation, so automakers typically limit it to about 50 mph and 50 miles total. Enter your spare type and the miles you've driven on it to see how much farther you can safely go.
A full-size spare, on the other hand, matches your regular tire's specs, so there's no strict distance limit. That said, it often sits unused in the trunk for years, so its pressure may have dropped and its tread may be old - check the pressure right after installing it and get it inspected at a shop soon.
Remember that any spare tire is a temporary fix. Even within the speed and distance limits, avoid sudden lane changes or hard braking, and get back to a full replacement tire or a repaired flat as soon as you reasonably can.
Frequently Asked Questions
A temporary (donut) spare is narrower and smaller in diameter than a regular tire, so it has less grip and weaker braking performance. It can also overheat and fail at highway speeds, which is why automakers cap it at about 50 mph and 50 miles.
A full-size spare matches your regular tires, so there's no strict limit. But since it often sits unused in the trunk, its pressure may be low and the tread may be old, so check the pressure once installed and get it inspected soon.
It's technically possible within the speed limit, but not recommended. Reduced grip makes sudden lane changes or hard braking risky, so it's safer to take slower roads straight to the nearest shop.