rear 190/55 r17?

[dcnblues]

We're really talking about a taller tire.

Without a wider rim, sure, I get that. But putting on a 200 will also widen the tire, and that's what I'm trying to focus on. The 200 will weigh more, and require more lean angle, so I'm leaning away from it but I'm not sure how good the software is to visualize these concepts in videos like this: *And it could easily be the case that the change is small enough that I really wouldn't notice it, but I still want to understand the theory...

Yeah they sure do! Look at the huge tires! An extreme example is the top fuel dragster. What I have been told is that the bigger and wider the tire is, the more matter there is to absorb tire heat. These tires don't have better traction because they have larger contact patches, they have better traction because they resist melting under 11,000 hp! Now look at the front tires of the dragster. They're like a bicycle tire but they have plenty of grip as long as they're touching the ground. Drivers have to keep that dragster straight and they need adequate grip in the front tires. They trust in a tire skinnier than a 600 cc sport bike tire to steer that dragster at 300 mph. Interesting to ponder all of this but I'm with you, I just trust a larger contact patch when I'm turning hard. LOL I'm not thinking about why I trust it when I'm riding the bike, I just trust it.

It's been so long since I used a stock sized tire on either of my bikes that I really can't compare how fast I corner with one or the other. To be perfectly honest, I think my skill has the most impact on how fast I corner. I probably would corner as fast on a stock sized tire. I've gone with lighter rims, aftermarket suspension and race tires. I'm not so sure any of those add up to higher speed in corners for me. It's a big bike, it corners well but it's still a handful no matter what you do. I can feel the improvements in equipment, I'm not so sure I'm good enough to really put them to their best advantage. It is really cool to feel it though.

Man the older you get the less frequently you get your mind blown. This has really rocked my world. Dragster tires have nothing to do with grip, they are heat sinks.

Excellent description, I'm largely in the same boat.

* I blew my budget on carbon rims, don't have anything left for aftermarket suspension. Never paid attention to lowering links, so missed out on the possibility of raising links for my gen 1. Now I have them on the Gen 3 and highly recommend them, but you may already have yours tuned for that.

 

[dcnblues]

...In the real world, we cannot apply pure math though, there are simply too many other variables:

A thinner tire heats up much faster, so the coefficient of friction changes fast, which makes a difference in traction.

Scates on an ice rink, the blades actually deform the ice, which changes sideways traction outside of what is accounted for in the formula.

If you are on a loose dirt road, a thinner tire makes more of an impression in the dirt, which changes everything.

Thanks, I'm starting to get it. It doesn't seem like traction is a limitation if you wanted to increase the size of the machines and consequently the riders, and consequently the American riders, in world class road racing. There are probably other real world variables which would be. I just wanted to live in a world where the fastest bikes and competitions were not tuned for midgets. Because then I could have street legal sport bikes that don't feel and look like children's toys, which the current liter bikes do when I sit on them.

This thread has been valuable because I used to think that it was tire limitations that would prevent you from a bigger and faster (hypothetical) category:

Pole time for Catalunya 2015:
MotoGP: 1m 40.546s (A Espargaro). Slowest: 1m44.3s
Moto2: 1m 45.895s (Zarco). Slowest: 1m48.8s
Moto3: 1m 50.137s (Bastianini)

 

[Mythos]

missed out on the possibility of raising links for my gen 1. Now I have them on the Gen 3 and highly recommend them, but you may already have yours tuned for that.

I have raising links. I'm pretty sure I got them from Schnitz. They're non adjustable and raise the tail one inch. They cost about 60 bucks a few years ago. One inch sounds like it will cause a shocking change in handling but I had a few members here recommend them and tell me the busa is still very stable with the aftermarket links. I have yet to install them permanently. I had them loosly fitted on the bike and they did indeed lift the height from the floor to the underside of the tail light by one inch with the bike standing vertical, no rider on the bike.

Getting back to tire width and lean angle, the animation in the video shows why a wider tire requires more lean angle. Maybe that's why the 190/55s and 200/55s I have used have that cross sectional elliptical shape. That shape would seem to reduce the difference between the center point of the bike and the contact patch compared to a circular profiled tire of the same width.

What about tire pressure? If your tire has lower pressure, that has the effect of making it skinnier than if it had high pressure...at least where the tire presses against the road. The tire flattens in against the road because the tire is softer with low pressure.

I've admitted to using wrong size tires on my bikes and using slicks on the street. I will also admit to using very low tire pressure. It increases the size of the contact patch. The added flexion in the tire causes it to build heat which is a good thing for traction up to a point. Really low tire pressure is horrible for some tires especially at low speed. Pirellis have very stiff sidewalls and I've gone down to 15 psi on the road without feeling the tire stretch sideways even in low speed cornering. LOL I tried really low pressure on less race oriented tires and I turned back home after 500 feet of very tame riding. Pirellis seem to tolerate low pressure very well. The Metzler slicks you see in my earlier pic did too.

Flexion of the tire causes heat in the tire. The heat in the tire heats the air inside the tire. Heat causes things to expand, gasses much more so than liquids or solids. Heating up your tire actually increases the internal pressure.

Centrifugal force of the rotating tire causes it to be thrown outward from its axis. In effect, the centrifugal force of the tire makes the tire grow in diameter and it makes the tire hold its circular shape, even against the pressure of the flat road surface.

If wrong tire size, slicks and low tire pressure isn't enough, I'll share another questionable experience with you. This one, I really don't recommend. I once road my 08 ZX-14 on a flat tire for over a hundred miles. I was riding home at night, I picked up a nail. Noticed the tire went almost flat to the rim while I was filling up with gas. Decided to try to ride from station to station to fill the tire as needed. Guess what? Many of the stations were closed and the air was off so I got back on the bike and rode it with the rim almost rolling on the inside of of the tire. I'm guessing maybe 3 psi. The low pressure caused a lot of heat in the tire which caused what air that managed to remain inside to expand and kind of keep the tire semi-inflated. I could see it going flat as I looked at it when I stopped. I'm sure the centrifugal force generated by riding 50 mph also helped keep the tire round instead of riding on a huge flat spot. I'll say this, the rear end sure did slop around even in the wide corners on the interstate. The tire was rideable though. Last 50 miles or so, I couldn't find an open station. The air pumps were shut down. One had a reasonable amount of air left in their tank so that helped but not very much. What helped most was the laws of physics coupled with a prodigious amount of good luck. The beads never blew out. I'm just recounting the story to illustrate how speed, tire pressure and heat affect tires. I certainly don't recommend anyone try what I did if they get a flat. This was a long time ago and my life was a lot different than it is now. ...not all in good ways. But just so everyone knows, it can be done. Lots of things can be done but I don't recommend trying a good number of them. this is one.

 

[Claude J. Greengrass]

I will post here the pictures of my tires, for the keen forensic tire analysts to leave their comments. Until now, my assumption is, mostly used center (thus worn) and sides less worn, so I ideally must be looking for a mileage-resistant tire, not a ultra sport one (always road-legal though).
thanks a lot!

 

[sixpack577]

You have alot of lean angle left, which would require alot more speed, or just excessive leaning, lol, to use the tires all the way to their sidewalls.
So your street riding is not excessive or aggressive, and you want tires that last for alot of miles.
Of course you want something that still sticks well, and can handle the Busa's weight.
You need Sport Touring tires, not Sport tires.
Most any sport touring tire, in Busa sizes, by a reputable brand, will serve you well.
Most are also decent in the rain.
So for Dunlops, you wouldn't want any of their awesome Sportmax Sport tires, but their Roadsmart series instead.
Michellin, Bridgestone and their competition all have similiar to choose from.
As to which brand to use...I won't start a tire thread, lol

 

[jellyrug]

I'm riding 55's as well, but in hindsight should probably go back to 50's as I don't ride that agressive on the street and need better mileage life.

The 50 has a wider contact patch in the middle, which will give you more tire life, while the 55 has more contact patch on the sides for more agressive riding.

Looking at your wear profile, you will get better mileage out of a 50.

In short the 190/55 is less of a flat profile in the center, compared to the 190/50 which has a flatter profile in the center.

 

[Claude J. Greengrass]

You have alot of lean angle left, which would require alot more speed, or just excessive leaning, lol, to use the tires all the way to their sidewalls.
So your street riding is not excessive or aggressive, and you want tires that last for alot of miles.
Of course you want something that still sticks well, and can handle the Busa's weight.
You need Sport Touring tires, not Sport tires.
Most any sport touring tire, in Busa sizes, by a reputable brand, will serve you well.
Most are also decent in the rain.
So for Dunlops, you wouldn't want any of their awesome Sportmax Sport tires, but their Roadsmart series instead.
Michellin, Bridgestone and their competition all have similiar to choose from.
As to which brand to use...I won't start a tire thread, lol

Just as an example, if I were to select Continental, between Sportattack and Roadattack I'd rather buy the Roadattack model (which incidentally comes more expensive), right?

 

[sixpack577]

Just as an example, if I were to select Continental, between Sportattack and Roadattack I'd rather buy the Roadattack model (which incidentally comes more expensive), right?

Yes, and sport touring tires are more expensive than sport tires...and both have went way up in price in the last couple of years

 

[jellyrug]

Short video of runout on my new Michelin Road 6 back tire. Think it’s gonna be a bit bumpy above 120 mph. Not the quality I would expect from Michelin.