I can get a deal on 4 michelin tires but they are 225/70r16 instead of 225/75r16. Except for ground clearance, anybody knows of adverse effect ( mpg + or - )

When your speedometer is reading 65mph you will in fact be going only 63.03mph. Your mileage will drop a little, very little. I wouldn't think it would cause any problems with your computer or brakes. But, it is your call to make.
You can go online and Google..tire calculator, this will give you an idea as to % of difference between the two sizes.

The tires are 3% smaller according to the charts.

You're going to undersize the tires??????

_________________
MUDD'S MOTORSPORT'S We do IFS lift installs ,
03 OVERLAND EDITION /Kilby-Skidrow-Mopar-4XGuard skids/ 2.5 inch TOTAL CONTROL JBA coilovers -JBA Arms/MOABS-31 FALKEN WILDPEAK AT3W / 4.10's etc, 04 Kilimanjaro Edition loaded, plus 05 KJ limited

3% undersize in height,what problem do you see ? It is about 1 in less, so about 1/2 in lower for the truck.The truck is mainly used for city and highway driving, wont see much trail.

Well, 3% smaller diameter could equal a 3% drop in mileage. Say over 40,000 miles would this 3% drop in MPG be more or less then what you are saving by buying these tires. Do you have 4 wheel drive, if so you need to make sure your spare is the same size as the 4 on the ground. Other wise you could drive your on board computer nuts, even more so if you have the Select Trac II.

Finally did not buy tires, came with 4 mags and 4 practically new michelins. tires were on the small side and the hubs were too small on the mags, would have to use spacers. Would have been a good deal at $425.00.

there's plenty of other good deals out there, just keep ya eyebawls peeled, if you're in the great lakes keep ya eye on greatlakes4x4 and naturally the for sale sections of every jeep forum you can figure

_________________
03 Renegade (Black)
177k miles 3.7L gas - 45RFE
Command Trac / 4.10s
Lift: ft. 790+ rr. JBA4+
The last of the TrailReady Front&Rear Bumpers and TR Rock Rails
Jarhead Offroad light covers
31x10.5R15 RedLetter Grabbers on Blackrock Dunes
L.O.S.T #KD098632