The usual recommendation is that you don't drive at more than 50mph and for more than 50 miles in one go. That is simply because the tyre is small and they don't want it to be unduly stressed, possibly displaying less reliable handling. The idea is that within that time you get your normal tyre repaired or replaced and put the space-saver back in the boot for future need.
Look at the tread wear, but it should be OK. I have driven a spare tire 300 miles in one trip, then a few other shorter uses, and it is still fine.
the short answer is, You can't. and it does not really matter how many miles a tyre has done so long as it still has plenty of tread depth. You can only guess at how many miles a tyre has been used by the amount of tread wear it has. You say it is supposed to be maintained at 60psi, seems a bit excessive to me for that size vehicle, I drive a 2 ton vehicle and keep my tyres at 35 to 40 psi and get thousands of kilometers out of them. Over inflation will cause excessive tread wear to the center of the tyre
It doesn't mean the tire is only good for 50. It means they don't want you driving more than 50 to get it fixed. See the difference? Some people go for weeks before removing the donut.
Do not worry about it These are excessive cautionary warnings. I can tell you that these tires will last for hundreds of miles at much higher speeds than the warning labels would allow. It will probably not last as long as a normal tire, but it will not magically self destruct at 50.0 miles
My car is a 2001 Daewoo Lanos it has been in my family since it was bought new in 2000 it was given to me when i got my license the family member that drove it before me had to use the spare donut tyre 2 seperate times when both front tyres went flat at seperate times. thing is i have no idea how many miles it was driven each time it was used. All i know about the spare is it is suppose to be inflated to 60psi. How would i know how many miles it has been driven on before?
