I need some help with crunching some numbers on final drive gear ratio.

The LX CVT has a final drive gear ratio of 5.44. Stock it rides on 185/60-15 wheels. When the tire diameter is changed to 185/60-14, what is the new final drive gear ratio?

All things being equal (Wheel weight and tire weight), what is the new theoretical hp/torque increase in %? Thanks for any help!


Edit: Bah...delete thread if you like. I think I found what I'm looking for here --> The Size Change Calculator

Stock LX CVT is 5.44. Changing from a 15" to 14" wheel diameter changes the ratio to 5.83:1.
Says Hi Gears: 4.62:1, New Gears: 5.08:1 and Lo Gears: 5.53:1 ?? Not sure what that means hp/torque wise either but I'll keep looking. Saving here for reference. Feel free to use the link for your own purposes.

Re-Edit: Stock-->
Engine HP @ rpm: 130 HP @ 6,600 RPM
Torque (lb.-ft. @ rpm): 114 lb.-ft. @ 4,600 RPM

 

Changing the tire size doesn't change the gear ratio at all. it does change the effective ratio which is what was calculated. The calculator in your link is overly simplistic because it doesn't use the actual rolling radius of the tires.

If you have data for the revolutions per mile (RPMi) of the tires (available on the Tire Rack site) all you have to do is multiply the actual axle ratio by the RPMi of the new tire and divide by the RPMi of the old tire to get the new "effective ratio"

So, take 5.44, multiply it by 914, divide it by 877, (using data for Kumho Solus KR21) and you get 5.67:1

However, with a CVT, changing the tires diameter may not change the overall ratio much at all. With smaller wheels the CVT will just select a taller gear to keep the engine in the same rev range as before. It is only at the extremes of the transmission's ratios that it will make a difference.

 

http://www.sohchonda.com/forums/topic/11187-effective-hp-or-torque-loss-vs-tire-size/

On my phone in Motor Vehicle and found the link. Saving to check later.

9 affective horsepower with no changes in weight.

8lb-ft of affective torque with no change in weight.