The best place to start is your owner's manual, which should list the exact recommended mileage for the spare tire. If you don't have a manual, 70 miles is the rule of thumb. Temporary, donut ...

"So we opened that up and realized there wasn't a spare tire." Her Jeep did not even include a temporary "donut" tire, just a little air pump. "This is what you get as an alternative to a spare ...