In a hypothetical situation with a truck that makes 550-650whp where traction is not a variable, how would 1/4 times be affected by going from a stock 31.5" tire down to a 30.5 or even 29.5 tire? Or 30" for that matter? I like the look of a thick sidewall and the truck seems to ride and drive better too. I really like my 31.5" 265/70/17 tires but I'm considering getting some lightweight 18s and doing a 285/60/18 which would be also 31.5". I just think a truck looks weird with 28" or 29" tires.

From my math, going from a 31.5" tire to a 30.5" tire would increase my final drive ration from a 3.42 to a ~3.53. That's not a huge difference. But a 29.5" tire would bring me closer to 3.73s...

 

you want a tire that would put you twords the top rpm range at the end of the run without shifting. really depends what rpm you are trapping at.

 

What is max power rpm
What tire height
What target mph

Punch those in calculator and youll see what gearing you want

 

Yep, depends on rpm, but everything else being equal you will be slower with a taller tire.

 

I definitely assumed that. I was just wondering if anyone had done any back-to-back testing with different tire heights to see just how much faster or slower.

 

A turbo vehicle is like any other vehicle...gear it for max power thru traps with largest tire youre allowed for best mph