hey maybe someone can help me. I have a 99 expy 4x4. the stock tire size is 255/70/r16. I put on a set of 265/75/r16 and it has a bad jerk to it especially towing. the jerk is almost like a skip but the motor is fine. i put the stock tires back on and no problem does anyone know what this can be?

 

Are they continental contitrac's?

 

no. they are Bridgestone desert duelers.

 

Are you sure it's not an engine problem. I had two coil packs go bad and I would have sworn it was my tranny. Everytime I started up the smallest hill, I would feel a jerk/skip. The taller tires would put slightly more strain on the engine that could cause the problem to show up easier.

 

Bingo!

Check your MISFIRECNT PIDs with a capable scan tool (not a code reader) to see where the weak cylinder is at.

Steve

 

will check those things, i did put the orginal tires back on the rear(trying to see if it was a rim or bad tire) with the taller ones on the front and it made a hell of a racket. does this make any sense? or if the coil pcks gone out wouldn't i notice it on the stock tires?

 

You should never run tires of different heights on the front and rear of a 4x4. It can cause the transfer case to bind up. That may be the noise you heard. Also, yes, if a coil pack was bad you should still feel it with the stock tires.

 

would i not notice this when pulling my race trailer? it is a 7x16 enclosed? just trying to find out before i spend the money on the scan job. thanks for all your help!!