I have mismatched tires in the rear due to one of the FD wheels cracking. Could the difference cause any sorts of noises from either being uneven or something to do with the diff?

 

Tread pattern can cause road noise. If you're hearing diff noise, maybe the two tires have different circumferences, and are spinning at different speeds. This might be making the LSD try to work all the time.

hmm, wouldn't that be bad for the diff/LSD? Maybe somone with more experience should chime in.

 

yes actually it is very bad. At my work (Town Fair Tire) on vehicles with awd you must match the tires ti 3/32 of an inch in tread depth.... so if they tires are a different size it can cause major issues. Even on RWD or even FWD cars. if a spare is to be put on a drive axle(the spare normally being a space saver ans smaller then O.E. rolling diameter) the spare would be moved to a non drive axle and the other tire would be put on the drive axle.

think about this. a tire with a rolling diameter of 25.3" will want to travel further then a tire with a rolling diameter of 24.9" . The axle on the side with the smaller tire would thus spin faster and could cause binding, grinding or even breakage inside the differential. On a car with a posi rear end, or a tight lsd, welded gears etc... you would also notice a griding noise or even a tire squealing when turning towards the side with the larger tire.

anyway... move your fronts to the rear (i am assuming that you still have the FD's up front) and then go out and get yourself a new set of wheels with properly sized tires!

 

When my car's drive shaft was going out, it made a constant grinding sound, pretty unbearable.

 

As I've said before, yes it could be tires. Change them to find out. If all the same size, put the fronts on the backs. My embarrassing story-My '89 TII back in 2001 was making a noise in the rear. Definitely a rear wheel bearing. It started after driving for a while, and would change the sound of the droan when wheight of car would drop eg uneven roads. So I bit the bullet and changed both rear wheel bearings at 155,000 miles. Not a bad job except for the ABS sensors. Had them out one night and put them back in the next. Took the car for a ride and same noise. IT WAS THE FREAKIN' TIRES. Falken with only 9,000 miles.