First off the TIRE BASICS:

1. The tire pressures listed in the manual are designed for carrying the max load of the bike which conforms to the maximumload rating of the tires! When you run reasonably lower tire pressures you will get a smoother, more complaint ride & more grip).

2. Tire Sizes: it is important to know how to read the numbers on the tire.

Example: 190/55/17

190 is the tire width in millimeters. These are not exact as you will find that no two manufacturers 180 or 190 size tires are the same width etc...

55 is the aspect ratio in that the sidewall height of the tire is 55% of the width (190*.55=104.5mm)

17 is the rim size in diameter

3. Tire choices:

Of the few different tires I ran on my 919 I preferred the Sportec M1's best for ease of turn-in & grip in dry conditions (BT-010's had better grip in the rain & the BT-014's just sucked all the way around) plus the M1's were only like $250 a set with better than average wear for a grippy tire.

But tires are just that preferences. You have to decide what tire gives you the feedback & confidence you need to ride comfortably. Most riders generally feel that Metzeler/Pirelli tires offer a common feel & feedback that many riders can get accustomed to quickly while Dunlop users & Michelin users have specific things they look for in their preferred tires like the rate a slide is intiated or how the profile of the front tire affects the speed of turn-in etc... None of the current "sport" tires on the market are "bad" tires they just have different feelings & feedback as well as strong points & weak points. Nobody can really tell you what tire you should be running. You have to decide for yourself based on your needs & riding style.

What I can say is don't expect sportbike handling & grip out of a touring type tire... If you want to ride aggressively then buy some sticky race type tires. Yes they will be expensive & yes they will wear out quicker than a harder touring compound, but you have to pay to play & if ya think $300+ for a set of tires expensive try pricing some new bodywork, gas tank or radiator after you wad your bike up... Remember it is always better to have more tire than you need than need more tire than you have.

Next we will lay out some more general definitions:

DOT Street tire: a tire approved by the Department of Transportation for use on public roads

DOT Race tire: a tire approved by the Department of Transportation for use on public roads, but widely regarded as a purpose built tire designed to sacrifice longevity & wet weather grip for better adhesion under dry conditions only.

Race Tire: any tire that does not carry a DOT approval rating regardless of whether it has rain grooves or not (slicks) that is intended for use on competition road courses.

Contrary to popular myth the main difference between DOT street tires & DOT race tires is not the rubber compound. It is the construction of the belting plies in the tire carcass.

The belting in street tires is designed to give more stability & better ride when the bike is upright whereas the belting in race tires is designed for better grip & stability at high lean angles.

We have all heard the stories about Ricky Racer crashing his bike cause he was running race tires on the street & couldn't keep them warm enough etc & while there is some validity to those stories because the rubber compounds are designed to work in certain heat ranges, the overall statement is false & usually nothing more than an excuse for rider error. Cold race tires still stick better than a cold street tire. Race rubber being a softer compound than street rubber will be inherently more grippy than a harder street compound. Now if you have just recently abused your race tire or have installed a race take off then you may have either not enough catalyst left in the tire to provide adequate grip or you may need to put in a little time to scrub off the dead layer of rubber to get to some fresh rubber with good catalyst in it.

"What the hell is catalyst you say?" Well what really gives a tire its grip is a chemical catalyst in the compound that when heated makes the tire adhere better to the road surface. The reason racers sell race take-off tires even though they have more than half the tread left is because they have burned the catalyst out of the tires through either too many heat cycles or simply too much heat was generated in the tire period & now the tire no longer functions to their satisfaction or required level of grip. The hardness of the tire compound is only one part in the factor on grip as is the temperature range they are designed to run in. Tires pushed beyond their temperature range for extended periods will start to delaminate (seperation of the rubber from the carcass). Now I don't know about who you hang out with, but I know only maybe a handful of guys that can actually overheat a tire during street use... Street riders as a general rule simply do not have to worry about getting any tire race or street into the proper operating temp range as a normal sport riding pace will bring the tire into a useable temp range.  Racers on the other hand have to be concerned with selecting the proper temp range due to the fact that delamination can occur if the tire is subjected to sustained temps above it's operating range.

Another misconception is the idea that race tires are no good in the rain because of their lack of grooves in the tread. While it certainly is true that a tire needs grooves to channel water away to prevent hydroplaning, the real reason for lack of wet grip is again the compound. Street tires generally contain lots of silica in them to provide better heat dispersion (aids in consistent tire operating temps) & wet weather grip.