How much if any difference will it change the gear ratio form a 108 1/4 tire to a 109 3/4 tire?

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The revolutions per mile will change. You can't actually change the gear ratio without physically changing the ring and pinion. I know that you meant what effective change, but it just bugs me when it is referred to as "changing the ratio". Take care. Tom Worthington

The difference between those two numbers is all you need to know.

109 3/4 is about 1.4% larger, so you will get about 1.4% more distance traveled for each rotation of the driveshaft.

Hypothetically, if you have a 4.10 gear and went from a 34.5 tire to a 35, the effective gear would be 4.03.

What are you trying to figure out with tire rollout difference? RPM change at stripe, or?
You might want to check out this site:
Wallace Racing Calculators

trying to see if it will slow the car down on 60 foot. sorry for any confusion

IMHO, the amount of change in your 60' is usually not going to be a lot for that difference in rollout. But it depends a lot on the converter, and the camshaft/torque curve of your engine. Even tire pressure will affect how much difference you'll see. If you've got a broad flat torque curve, and a loose converter, it may not change a bit. I made a 2" difference in tire height and it didn't change my short times at all, though it did affect RPM at stripe.