Tire Size

[mcdonaldroadcapt]

I posted this under Harley Trikes with no response so I will try here. I am running 225/60/15 rear tires on my Trog. I want lower gearing without the costs of changing sprockets. My tires are needing to be replaced and I want to go to 225/50/15 to lower the ratio. Has anyone tried this combo? Also can someone do the math for me? I know bike will sit 1 3/4 inch lower but I can accommodate that with air suspension.

Thanks for any help.

Jim

[Gorilla]

Iposted this under Harley Trikes with no response so I will try here. I am running 225/60/15 rear tires on my Trog. I want lower gearing without the costs of changing sprockets. My tires are needing to be replaced and I want to go to 225/50/15 to lower the ratio. Has anyone tried this combo? Also can someone do the math for me? I know bike will sit 1 3/4 inch lower but I can accomodate that with air supension.

Thanks for any help.

Jim

Jim probably no one has done this. Sorry you need the circumference of the tires to do the calculations.

[mcdonaldroadcapt]

Circumference of 225/50/15 is 74.92 inches. Can you calculate?

thanks.

[Papa Zook]

I posted this under Harley Trikes with no response so I will try here. I am running 225/60/15 rear tires on my Trog. I want lower gearing without the costs of changing sprockets. My tires are needing to be replaced and I want to go to 225/50/15 to lower the ratio. Has anyone tried this combo? Also can someone do the math for me? I know bike will sit 1 3/4 inch lower but I can accommodate that with air suspension.

Thanks for any help.

Jim

The change from a 225/60/15 to a 225/50/15 will add a 6.9% gain in your speedometer reading, meaning that when your speedometer reads 60 MPH you will actually be running 55.9 MPH. There are several speedometer calibrators available, one of the better ones being the Speedo Tuner which sells for about $99 for the Big Twin HDs. Link Below.
Speedo Tuner

[mcdonaldroadcapt]

Thanks for the info. Will proceed.

[Papa Zook]

If you need any more size calculations try the site link below. Just plug in the tire sizes and it will calculate everything for you. Very handy little tool.

Tire Size Calculator



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[mcdonaldroadcapt]

Thanks for info on site.

[1550vt]

I remember posting on this topic elsewhere, but you can change gearing rather easily by changing tire aspect ratio. I shortened my gearing 4% by going to a rear tire 1-inch smaller in overall diameter. You will need to mind your ride-height and not go too far. A 1-inch overall reduction will lower the ride-height by 1/2-inch.

[mcdonaldroadcapt]

Thanks. I finished the application from 225/60/15 to 225/50/15 and love the results. Sweet spot is where it should be and no bogging off idle. Speedometer off a little but who cares? Very well pleased and with two up and air bags pumped to 30 lbs no tail dragging.