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[Richard230]

Alex, curious why going with a bigger tire would negatively impact range? In my head, my logic went like this: smaller tire = more torque = higher rpm at given speed = less range, and larger tires the reverse. Would that not be so?

In general, larger tires can result in poorer handling due to the cross-sectional profile changing. They also typically are heavier than a thinner tire and that will slightly degrade the suspension compliance.

[JaimeC]

Alex, curious why going with a bigger tire would negatively impact range? In my head, my logic went like this: smaller tire = more torque = higher rpm at given speed = less range, and larger tires the reverse. Would that not be so?

In general, larger tires can result in poorer handling due to the cross-sectional profile changing. They also typically are heavier than a thinner tire and that will slightly degrade the suspension compliance.

Another consideration:  A larger tire has more surface area which means it will dissipate heat more than a narrower tire.  It's the real reason high performance sport bikes have such large tires.  It doesn't give the tire more grip surface; it allow the heat to dissipate more rapidly.  The problem is, with the larger tire you MIGHT not be generating enough heat in order to get maximum grip.

Motorcycle engineers design bikes as an entire system.  Smaller bikes with less horsepower don't need big tires because they won't be able to generate enough heat which is why their tires look "skinny" compared to the bigger, more powerful bikes.  As Richard pointed out, there is a weight difference as well.  The stock suspension is set up around the recommended tires.  Sidestand, too.  Raise the bike a little higher with a bigger tire, and the bike will have to lean over that much farther on the sidestand.  I see people here already thinking their Zeros lean over too far.

My old R100RT had really skinny tires compared to the other bikes at the time, but only one or two of my riding buddies could keep up with me once I got moving.  The meager 60 horsepower was only half what a typical 1000cc bike put out so it did just fine with the stock tires.  Did fine at Pocono Raceway when I took Reg Pridmore's C.L.A.S.S. too.  I got dusted in all the straights but made up lots of time in the turns with that bike.  Still sorry I sold it to my buddy (wonder if he'll sell it back to me?).

[Crilly]

The bigger the tire, the farther the bike goes compared to the speedometer.  So does it really get less mileage?

[dennis-NL]

DS, Avon Trailrider.
Makes more noise then Michelin Annakee, but ride good and looks great.

[Killroy]

On the S/SR the stock size is 140/70/17, I found a deal on-line to a tire that was recommended, but it only came in 150/70/17.  At a friends recommendation, I tried it and the width looked great and the tire shape was much nicer than other tires I tried at the stock size.

I kept the front tire the same, but I never noticed that the rear tire was slightly larger in diameter.

My front tire tends to wear out a sooner, so it would make sense to try going from the stock 110/70/17 to 120/70/17.  Anyone have any issues with that.  You get more tire options those larger sizes.

I'd be wary of not only upsetting the geometry of such a slight bike, but destroying the range with 120 front and 150 rear.  I'm pretty sure the Zero engineers are half decent and did enough testing to reason the stock sizes.  I wonder what sizes they ride on their own SR's.

I'm going with the Michelin Power RS's in stock sizes next.

To clarify, I ran the "wrong size" - by 5 mm on each size -I wonder if anyone can even notice this visually without measuring.  FYI, there is a nominal value and a size tolerance and tires in general are notorious for not being nominal size. 

I tried the stock Diablo Rosso for the life of the tires and found a weird wear pattern basically on the same  windy mountain highway that many Zero employees  ride to work.  My work at the time was blocks away from Zero's and I would often ride with zero employees to work by happenstance. 

I don't know the motivation of selecting the Diablo Rosso and the tire size, but I bet it has to do with cost a lot more than you think.  Zero is a lean organization, its trying to make a profit and sales are low.  I am not sure if they have time to do real tire testing.  Zero employees might be riding Diablo Rosso because that is what they have laying around.

The "right" tires for the motorcycle should be up to the rider needs.  I like the idea of a little extra rubber and I have had good tire shape and wear results for the life of basically the same tires (Bridgestone T30 before, now T31).  Also, originally I found a deal and since tires are one of the largest cost of motorcycles, tire cost is a big factor.  Yes, tire diameter is slightly different.

[togo]

> The bigger the tire, the farther the bike goes compared to the speedometer.  So does it really get less mileage?

Such a fun comment.  I don't know where to start.