Tyre Pressure

[low drag]

well if people need to be told that a car tyre has a flat profile and a motorcycle tyre is rounded then they may need to find out that cars have 4 tyres and motorcycles only have two ...

I'd like to impose upon you if I could..... I just installed some new tires, Shinko 705s, they replaced K60s. The profile is defiantly more rounded and handle much better on the street and trails.
I have a few hundred miles on them (mostly road but a good bit of gravel roads and trails) and noted the center of the back tire is showing tread wear (I just took my tread gauge to them this AM). Max pressure on the sidewall states 42 psi, I'm running 38 psi. I'm a bit surprised to see some thread wear this soon.

So to my question. To reduce tread wear should I increase or decrease the rear tire pressure?

 

[shrekonwheels]

That sounds more like a softer tire, but running the proper PSI reduces wear in general. Lower PSI means a higher contact patch thus increasing wear.

 

[Checkswrecks]

I'll agree with what Shrek said, adding that the Shinkos are known for short life.

 

[low drag]

That sounds more like a softer tire, but running the proper PSI reduces wear in general. Lower PSI means a higher contact patch thus increasing wear.

Any idea how to determine what the proper PSI is for a given tire and rider combo?

I'm thinking of bumping mine by 2 PSI up to 40. The sidewall states 42 is max PSI for this tire.

I take it the heavier the load the higher the PSI should be?

 

[shrekonwheels]

Any idea how to determine what the proper PSI is for a given tire and rider combo?

I'm thinking of bumping mine by 2 PSI up to 40. The sidewall states 42 is max PSI for this tire.

I take it the heavier the load the higher the PSI should be?

Everyone has their opinion, but I usually just check my pressure every couple months or so and try to run it at factory recommended pressures. It allows me to corner carve which I am well known for and haul just fine. When I was on the track then I messed around with various pressures, but honestly for what we are doing I do not see the point. Its really hard to find an exact pressure when your road and lines are constantly changing.

I cannot make that decision for you, but I would recommend you picking a the max pressure as stated for your tire and learning to set up your suspension which will drastically change everything.

 

[Checkswrecks]

Any idea how to determine what the proper PSI is for a given tire and rider combo?

I'm thinking of bumping mine by 2 PSI up to 40. The sidewall states 42 is max PSI for this tire.

I take it the heavier the load the higher the PSI should be?

Yamaha's book values are 33/36 for a number of reasons, including handling. Many people will exceed this and some will exceed the max shown on the tires. I'm not saying if right or wrong, just that others have shown that what you propose has been done before.

 

[frez]

The manual shows 33/36 for loads less than 90kg/198lb and 33/42 for loads over this.

Michelin, Bridgestone, Avon, Pirelli and Dunlop all say 36/42 (2.5/2.9 bar) for their tyres.

From this I assume anywhere between 33 and 36 for the front, and between 36 and 42 for the rear are fine.

I run mine at 36/42 because I load the bike way over 198lb.

 

[low drag]

Yamaha's book values are 33/36 for a number of reasons, including handling. Many people will exceed this and some will exceed the max shown on the tires. I'm not saying if right or wrong, just that others have shown that what you propose has been done before.

I don't have the OEM tire (which is what I assume the manual states pressure for), when I bought the bike it had K60s on it. Those stated max PSI at 36. Now I have the Shinko 705s, it states a max PSI of 42.
I'm fairly new to motorcycles, I got my 1st one 2 years ago yesterday (well took it home from the dealer) and traded up to the ST last June. The tire thing is still leaning to the MoJo side for me right now. I know the better grip the tire gets on pavement the softer it is and the faster it will wear. The harder it is the longer it'll last but it won't have the 'stick' of a softer tire. Beyond that it all seems like a guessing game to get the right pressure. I assume the same will apply when riding trails and encountering rock, shale and gravel.....
I guess I have to resign myself to going through tires 2X per year, for the rear at least, and try to record my pressure and results.

I have noted that I lose air pressure after a couple of days though, so I always check pressure before a big weekend ride.

Thanks guys.

 

[shrekonwheels]

Uhgg a big can of worms on tire pressure recommended by the tire manufacturer or Yami, I think the tire manufacturer, run its recommended pressures.

Honestly unless you are a superstar you cannot tell the difference on the road, the bike should out handle your capabilities. I promise I have been riding for 39 years now (Ten more gray hairs popped up as I typed that) and since 90 on the street, just ride and do not over think, Trust your tires! ::021::

Now off road you will notice pressures a bit more, Ideally you should carry a pump and put air back in on the road.

If there is an offroad clinic that would help, and hell, if you can pick up a cheap dirtbike to beat the hell out of that works too.