Any prbs,my car is Pontiac grand am gt and i put 2 used tires(225,60R16) on front

[pavan k]

and back are new(225,50R16)? hello every body, i am having 1999 Pontiac grand am gt and recently my car driver front tire gone worse so i replaced both front with 2 used tires which are of size 225,60 R16 but i have 2 new tires on back which are of size 225,50 R16. so is there any problem with mileage or speedometer or the life of the car.

 

[Daniel R]

your ABS will not work correctly because of the difference in diameter of the tires.

 

[Oreif]

The stock tire size was 215/60R15
with a 225/60R16 your speedo will be 5.9% too slow.
This means when your speedo says 60mph you are really doing 63.5 mph

When you had the 225/50R16's on the front your speedo was off by 1.2% too fast so when the speedo said 60mph you were really going 59.3mph

With the 225/50's in the rear and the 225/60's up front the height difference between front and rear is over 1.5" difference. So your front end is higher. This will change your weight distribution which could affect the ABS, braking, and handling.

235/50R16 would be the plus size tire for your car. So if you were to get 4 new tires in this size your speedo would read the same as if there were stock tires on it.