160/80 tire slowing Nad down?

[moenko]

Hi again, I'm full of questions today ::)

I recently changed from the stock 170/70 Brickstone to a Metzeler ME880 160/80 in the rear. The 160/80 has a slightly larger overall diameter (turns about 21 times less per mile than the original tire).

My questions to the math and wrench gurus: I was barely getting the good bike up to 90 mph (GPS) where before I would have no problem getting up to around 100 mph (again, GPS speed). I was in 5th gear and know you won't hit top speed in overdrive, but for some reason the bike is noticably slower.

Could the larger diameter of the rear tire be the reason for that (perhaps it requires more HP/Torque to achieve the same speed)?

[Yellow Jacket]

The difference in diameter should only be about .71" with a difference in circumference of 2.23".

This would have the effect of making each gear just a little taller by 2.8%. Since the Overall Drive Ratio is 3.105 in 5th gear this would change that to 3.018.

I don't feel that this small of a change should make much of a noticeable difference in your top speed.

It would however decrease your speedometer error by about 1.8 mph.

[moenko]

Bob, appreciate your reply and yes, I noticed the speedo is a bit more accurate now than it was before. Well, looks like I will have to look for the "sluggish" performance somewhere else, plus I will get a little more mileage out of that rear tire! Thanks again!!

[ells]

Moenko,

I had that size/make of tire and never noticed any loss of high end, although didn't test it often. Got more than 15K mi out of it too.

[Jared]

Originally Posted by Ells

Moenko,

I had that size/make of tire and never noticed any loss of high end, although didn't test it often. Got more than 15K mi out of it too.

15K miles? What brand was that?

[moenko]

The Metzeler Marathon ME880 (rear tire is still made in Germany, front is made in Brazil). I have heard of that kind of mileage on the ME's before - they outlast most others.

[ringadingh]

I have 12,000 miles on my rear ME880 and it could easily go another 3-4000 miles. My front ME880 has 20,000 miles and still running. Im probably going to replace them shortly but thats because Im trying to cure a front end wobble.

[ells]

Originally Posted by Utah Motorcyclist

15K miles? What brand was that?

Yup, the ME 880 like Moenko says. Had decent, maybe 2/32" left on it but wanted new tires for the summer. The front was about equally worn but with a couple less K mi on it, go figure - yes it was Brazil made and the rear German. But the airplane I rode on yesterday, American Airlines from Chicago to Louisville, was made in Brazil too, at least it said "final assembly Brazil" and that worked out okay.l

[sarge1057]

It sounds like you may have stayed in a Holiday Inn Express last night.