Relation between tire size and gearing

[groundhogday1976]

Okay, I know that increasing your tire diameter will make for higher gearing, and decreasing it will make for lower gearing. Is there a formula I can use to plug in say, fifth gear, final drive, and tire diameter to get gearing so I can tell how much changing tire heights will change things?

[sultan]

this one shows what your rear end gearing, and speedo error are: http://www.c5-corvette.com/tirecalc.htm