Hello

Anybody known with this problem.
When I drive on the highway in overdrive, It keeps shifting down and up?
Could it be that I now have 33'' tires before it had 31''.
I believe it was ok with the 31'', not sure tho.
I think it should still work with 33''.

 

What are you driving?

33's without a gearing change will likely be too much for your engine to maintain speed in over drive which will cause the symptoms it sounds like you are experiencing.

 

I have à 1989 k5,
Thanks for the info

 

What gears do you have in there now? My '74 will keep up on the highways just fine with the 33x12.5 M/T's, but I have 3.73's and do not have an overdrive transmission.

From the sounds of it, you maybe have 3.42's or possibly even 3.08's which would be miserable with large tires.