I would agree witht hat mostly, BUT I have just put 33x10.50s on my 88 Troop with the 2.6 and my power did NOT go down at all. The thing to look for is the width of the tire...that seems to really zap the power

My .02,
Chris

1988 Trooper: 2.6L Delta Cam, Pacesetter Header, K&N, 2 1/4 exhaust, CB, Lights by Hella, Warn Hubs, 6.5 inches of lift thanks to DOR and PA, Rancho 9000x's, 33X12.50 Durango MTs
1995 Nissan Maxima...the DD :-)