Rear tire sizing and possible gearing affects

[troop]

Hey all,I wanna pose a question to those who are running (or have run) rear tires in the 205/60 or 205/65 sizes. Curious as to both the speedo correction factor and possible gearing effect. I have a 2019 F3-S, and while not opposed to a slightly taller gearing effect, I'm not really interested in getting a lower effect when traveling down freeways on trips. I can't remember my speedo reading versus actual, but IIRC, I believe my speedo was approx 2mph optimistic over actual. Thanks for any experienced input :)

[cruisinTX]

I just shared a chart on the other thread, "REAR TIRE". take a look at the correction that is achieved with 215/60 and 205/65.

[Fearless]

Try this site
https://tiresize.com/comparison/
gives a good comparsion of sizes.

[BLUEKNIGHT911]

Try this site
https://tiresize.com/comparison/
gives a good comparsion of sizes.

:dontknow: Except that it not accurate ….. the chart was created … Mathematically … I can pretty much guarantee that every manufacturer of say 215/60-15 will actually have a different circumference ( which means Size ) for that size and any other size you apply it to ….. Mike :ohyea:

[troop]

Interesting website, thank you. Yup, although I haven't looked at specific dimensions of rear tires for the Spyder, I did look at tire specifics on past motorcycles. And true enough, specifics varied by mfrs. That said, with my OEM 225/50R15, my speedo is approx 2mph optimistic. 215/60, 205/60 and 205/65 all will speed up the speedo a touch. The chart would indicate the 205/60 would almost bring it to dead nuts. Probably overthinking the gearing effect :)

[AeroPilot]

The nominal tire sizes will give you a good idea but slight manufacturing differences probably also change the actual speed at the road surface (as does tire wear). Yep you might be overthinking it.

We all like to tinker and experiment, and this is acceptable staying within a couple ranges of sizes from the original 225/50 R 15 profile rear Kendas.

They all will give acceptable gearing within 1-2 tire width/percent profiles ranges with the torque you have from the 1330 engine and 89 tooth sprocket on your F3S..

Our 16 F3T runs down the road within 1 mph of actual speed on a 215/60R15 General Altimax - https://www.spyderlovers.com/forums/showthread.php?128032-Rear-tires&p=1490357#post1490357

[h0gr1der]

Interesting website, thank you. Yup, although I haven't looked at specific dimensions of rear tires for the Spyder, I did look at tire specifics on past motorcycles. And true enough, specifics varied by mfrs. That said, with my OEM 225/50R16, my speedo is approx 2mph optimistic. 215/60, 205/60 and 205/65 all will speed up the speedo a touch. The chart would indicate the 205/60 would almost bring it to dead nuts. Probably overthinking the gearing effect :)

Mr Troop,

I am currently running the Vredstein 205/60R15 on the rear, and there is still a 1 MPH discrepancy at 70 MPH versus the GPS. Next time I may give one of the 215/60R15 tires a try, see if that evens it up.

[Highwayman2013]

Our 2016 F3L is also within 1 mph of GPS speed with a General Altimax RT43, 215/60/15 with 20,000 miles on it.

[IdahoMtnSpyder]

Our 16 F3T runs down the road within 1 mph of actual speed on a 215/60R15 General Altimax -
As does my 2014 RTS with the same size Cooper Grand Touring.

[PMK]

Troop, no plans to debate tire brand or size. Suggesting though that with your research place less emphasis on these generic tire size comparators and for truer numbers use the tire manufacturers website data. Typically they list all kinds of stuff, but importantly revs per mile.

Two like size tires, from two different companies can be considerably different in actual measured size and revs per mile.