[Miata] driving on the donut spare (NMC)

[Jones]

A friend with a Scion tC called me to help with a flat tire last night. 
The tire has two nails and won't hold any air. Today is Easter so all 
the tire shops are closed. I put the donut spare on the car so she is 
not stuck at home till we get a new one. I kept the bad tire and was 
planning to get it fixed/replaced tomorrow morning and then put it back 
on the car in the evening.

She wants to know if she can drive to work on the donut tomorrow. Her 
commute is a 50 mile round trip with about 75% of it on the highway. We 
don't know where the car's manual is so we don't know what the mfr 
recommends.

 From what I read on the net, you shouldn't go more than 30 miles on the 
donut spare and you shouldn't exceed 50 mph. With the car being a FWD, 
mismatched tires on the front is probably not good for it.

My suggestion is that she leaves the car at home till she gets the new 
tire in the evening. Does that make sense or am I being too paranoid 
about damage from driving too far on the donut?

Adding a little Miata content - my car has not had a spare in about two 
years. I drive around with a can of fix-a-flat. Trunk space is too 
precious to give up so much for the spare.

jmb