yesterday i picked up some stock 17's off an 07 tahoe and had them mounted up on my obs 97 4x4 tahoe. the new 17's have a 265/70/r17 tire on them, the tires i had on my tahoe before were 245/75/r16. after i got them mounted up i was driving on the freeway and when i would hit about 70 the tahoe felt like there was something going on with the rear end. last night i had my tire size calibrated and now its even worse, i will be driving at 70 and all the sudden it feels like my engine is bogging, but it is coming from the rear end and it shakes/vibrates fairly severe and then stops.. it happens about once everytime i am doing about 70 on the freeway and after it stops it wont do it again until i get back on the freeway. i do not notice any of this around town, but then again top speed in town is like 50...can anyone help tell me what the problem is?