Does tire size count?

My 89 with 302 fi engine runs very rough and seems to mis-fire under acceleration. It has 97,000 miles on it.I was wondering if the larger than original tires are causing it?
Runs at high speed OK. Mostly runs rough under load in mid-range. I put new plugs in it and a new fuel filter coming from gas tank.
Whutca think? Chuck
http://cmbtow.com

tires have nothing to do with the car running rough.

hey i have a 94 p71 with the 15s on it. i have the chance of putting the 16s from the 98-present on it. will it be possible without any problems?

'98 - '02 16" wheels will work on '92 - '97 CV's & GM's. The inset is different on the '03s.

Check the rest of the ignition system to make sure you aren't losing spark before it gets to the plugs. If spark is OK, you may have a clogged/faulty fuel injector.