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Old 02-06-2011, 02:38 PM   #1 (permalink)
abell75
EcoModding Lurker
 
Join Date: Nov 2010
Location: St. Louis
Posts: 38

Grand Prix - '02 Pontiac Grand Prix GP
90 day: 24.01 mpg (US)
Thanks: 3
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Larger Tires to Increase Gear Ratio

I'm considering larger diameter tires for my Grand Prix next time I need to buy them. Reason would be to reduce my engine RPM at cruising speed (I have plenty of power and want to get closer to optimum BSFC on the freeway when I need to maintain a constant speed instead of P&G.

My speedometer will not be accurate. I'm ok with that.

But if my diameter goes up 2" then my ride height goes up 1". Will the height increase cancel out some/most/all/more than all of the ratio improvement? Maybe it just means I need that underpan mod as well!

Thanks,
Aaron

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