Spare tire is .61" bigger than the mounted tires

[jtvang125]

My spare is 17" with overall diameter of 25.33". The mounted tires are 18" with 24.72" diameter. If I get a flat on a last distance trip and had to use the spare for the rest of the way would it be bad for the transmission or differential?

 

[SpeedEng66]

no nothing bad would happen

edit
im guessing you put new tires/rims on what was the oem tire size
by changing the oem to low pro tires you changed the speedo readings
fyi

 

[ValValline]

The difference is not great enough to cause problems unless you put thousands of miles on the spare. Even then I doubt it would do much harm if any.

 

[kami333]

You could put them on a non-drive wheel if you are really worried.

 

[Summitdrinker]

making a guess and adjust air pressure of the two tires on the same axle to get a closer dia if it bothers ya much

years ago when I was young and broke I did this with tires that didn't match on the back of RWD cars

 

[Zenmervolt]

Unless you have some sort of limited slip differential, there won't be an issue with using that tire as a spare.

ZV

 

[jagec]

It just means that one side would be spinning slightly faster than the other...which happens every time you turn a corner anyway.

Driving with the spare would be like taking a 300-mile-long gradual curve, as far as the car's concerned. Not a problem.

 

[JulesMaximus]

Originally posted by: jtvang125
My spare is 17" with overall diameter of 25.33". The mounted tires are 18" with 24.72" diameter. If I get a flat on a last distance trip and had to use the spare for the rest of the way would it be bad for the transmission or differential?

Is this a temporary spare or a fullsize spare? If it's a temporary you shouldn't drive on it for more than it takes to get to a service station to get your flat fixed or replaced.

 

[boomerang]

Originally posted by: JulesMaximus

Originally posted by: jtvang125
My spare is 17" with overall diameter of 25.33". The mounted tires are 18" with 24.72" diameter. If I get a flat on a last distance trip and had to use the spare for the rest of the way would it be bad for the transmission or differential?

Is this a temporary spare or a fullsize spare? If it's a temporary you shouldn't drive on it for more than it takes to get to a service station to get your flat fixed or replaced.

Yes, the spare will have this information (in condensed form) right on it, molded into the sidewall. The owners manual will say this also. They're really not meant for long distance driving. IIRC, 50 miles is the limit.