About 50 miles, at no more than 50 mph, if it's the small donut spare. That's the limit on the sidewall of most compact spares and in most owner's manuals, and it's a real limit, not a suggestion. A full-size spare that matches your other tires can go as far as you want.
Check the pressure before you drive on it. Donuts need 60 psi, and the one in your trunk has probably been losing air for years.
What the 50/50 rule means
The donut is a different tire, not a smaller version of the same one. It's narrower, has shallow tread, a lower load rating, and usually a smaller rolling diameter than the tire it replaced.
Kia's current owner's manuals spell out the restrictions. Don't go over 50 mph. Inflate to 60 psi. Don't fit tire chains to it. Don't take the car through an automatic car wash with it on. Don't tow a trailer. Don't run two compact spares at once. The manual also warns that the smaller spare drops ground clearance by about an inch.
The 50-mile distance isn't in Kia's text; it just says continuous use "could result in tire failure, loss of vehicle control, and possible personal injury." Les Schwab and Jiffy Lube both give 50 miles as the usual limit. AutoGuide notes some spares are rated to 70 miles. The number on your own spare's sidewall wins.
Why the limit exists
Tread first. A donut carries maybe a few 32nds of tread, and it wears fast because the narrow tire carries the same corner of the car.
Diameter second. Because the donut is smaller, it spins faster than the other three. On a front-wheel-drive car that means the differential is working the whole time you drive. On many all-wheel-drive cars, the center differential or coupling does the same, and that's where expensive damage happens. Kia's manual warns against hard acceleration or braking between 0 and 25 mph on the spare because it can push oil out of the transfer unit.
Braking and handling third. Les Schwab's warning is that the differences "can limit stopping power, safety, and overall control." The ABS and stability control are also reading a wheel spinning at the wrong speed, so expect warning lights.
How far you can go, by spare type
Spare type | Speed limit | Distance limit | Pressure | Notes |
|---|---|---|---|---|
Compact donut (T-type) | 50 mph | About 50 miles, some rated 70 | 60 psi | Replace with a real tire as soon as possible |
Full-size matching spare | Normal | No limit | Placard pressure | Rotate it into the set, check age |
Full-size non-matching spare | Normal | Short term | Placard pressure | Different tread depth or brand; swap off soon |
Run-flat tire after puncture | 50 mph | Up to 50 miles | Whatever is left | Bridgestone DriveGuard Plus rating; most run-flats are similar |
Sealant kit (no spare) | Normal | Get to a shop | Reinflate per kit | Sealant can make the tire unrepairable |
A full-size spare is only "no limit" if it's healthy. Spares age in the trunk, and Jiffy Lube puts the useful life of a temporary spare at about eight years. The DOT date code on the sidewall tells you the week and year it was made.
Run-flats are their own case. Bridgestone's DriveGuard Plus is rated for up to 50 miles at up to 50 mph with zero pressure. Once you've driven on it flat, it probably can't be repaired, so plan for a new tire.
Pressure, and why your spare is probably flat
Compact spares want 60 psi, far more than the 32 to 36 psi on your main tires. Jiffy Lube's figure is "around 60 psi," and Kia's manual says exactly 60 psi (420 kPa).
Nobody checks the spare. A donut that's been in the trunk for five years can easily be at 20 or 30 psi, and a donut at half pressure is a tire that will overheat in a few miles. Check it twice a year, or at least before a road trip.
The same goes for the jack and the lug wrench. Make sure they're there and that the wrench actually fits your lug nuts, especially if the car has aftermarket wheels or wheel locks.
What a replacement spare costs
More than you'd think new, almost nothing used. A thread on Bob Is The Oil Guy quotes $230 for a Goodyear convenience spare on Tire Rack and a $143 factory full-size spare option, while members report complete compact spares from junkyards at $10 to $25.
If your car came with a sealant kit instead of a spare, a used donut and wheel from a junkyard or eBay is the cheap fix. Match the bolt pattern, center bore and overall diameter, and confirm it clears your brakes.
What to do today
- Read the sidewall of the spare for its speed and distance rating. Most say 50 mph; some give a mileage.
- Check the spare's pressure. Compact spares need 60 psi; a full-size spare needs the door placard figure.
- Plan the next 50 miles. Go straight to a tire shop, not to work and back for a week.
- Keep it under 50 mph and off the highway if you can. Take corners and braking gently.
- Once the real tire is repaired or replaced, reinflate the spare to 60 psi before it goes back in the trunk.
Sources
- Kia Owner's Manual (2024, model code ON): Important - use of compact spare tire
- Kia Owner's Manual (2025, model code MQ4A): Important - use of compact spare tire
- Les Schwab: How Long Can You Drive on a Spare Tire?
- Jiffy Lube: How Long Can You Drive on a Spare Tire?
- AutoGuide: How Far Can You Drive on a Spare Tire?
- Bridgestone: DriveGuard Plus run-flat
- Bob Is The Oil Guy forum: Ridiculous cost of temp spare
Featured image: Donut Spare Tire by josbert.lonnee (public domain). Source
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