It's recommended that you should only drive on a spare tyre for, at most, 50 miles (80 km) and should not exceed 50 mph (80 km/h). However, depending on the type and condition of the spare tyre this may vary.
The Department of Transport in the UK recommends that you replace a punctured tyre with a new one as soon as you can. Only drive on a spare tyre for as long as is absolutely necessary.
Spare tyres are only designed to be temporary replacements and are not intended for prolonged use. They have a limited lifespan and may have speed and distance restrictions printed on them.