Transmission shifting with bigger tires?

[OrangeCrush]

In response to another post by a new member, he was asking about putting 39's on his H2.

It reminded me that I wanted some opinion from those that have bigger tires.

Obviously putting larger tires will give the same effect of reducing the gear ratio. I've noticed that around 45 mph, the trans can't stay in overdrive for long... the littlest incline or step on the gas pedal sends the trans downshifting into drive until it reaches the appropriate speed.

If I remember correctly, the trans is a 4le60 and shifts by speed, not rpms. Did anyone have their PCM reflashed to change shift points?

The speedometer with 38's is only off (according to those highway side portable radar units) 2-3 mph.

Anyone do anything about it or just leave it?

Thanks,

Mark