Pretty generic tyre pressure thread...

**cowboyz** · 6th August 2010, 14:55

right. I am running pilot powers now on the bike..

There are loads of things that determine ideal tyre pressures and stuff and thinking my recent off was contributed to by low tyre pressure (as I found out my guage is faulty and was reading 30 when my pressure was actually 23) but aside from that.. My question is..

normall road riding I ride with 37r/35f Feels good and stable
2up or touring I ride 42r/38f

racetrack I reset them both to 30 (or try to . ahem...)

anyhow.. my question is... on the basics of less pressure = longer heat up times but more grip.. more pressure = shorter heap up times but less grip.. (getting really laymans here)

if it is wet track.. running do approved tyres... would you go up or down in pressure or just not worry about it and stick with the 30.30 that everyone seems to think is a good baseline?

**Kiwi Graham:Me** · 6th August 2010, 16:16

If its any help:

I run 30 psi front dry or damp, 27 psi rear dry or damp power one B's

In the wet I run full wets 22psi rear 30psi front.

Edit; these are measured cold!

**cowboyz** · 6th August 2010, 16:40

yes.. assuming all pressures are cold...

right..

22 in wets.. assuming this is with tyre warmers? Woudl I be correct in saying that it would take forever to warm tyres up from 22 psi without warmers?

**Kiwi Graham:Me** · 6th August 2010, 16:49

Originally Posted by cowboyz

yes.. assuming all pressures are cold...

right..

22 in wets.. assuming this is with tyre warmers? Woudl I be correct in saying that it would take forever to warm tyres up from 22 psi without warmers?

Its been a while without warmers but a couple of sighting laps then start building the pace would be about right. Generally soft tyres (be that compound or pressure) take a shorter time to warm up.

**sharky** · 6th August 2010, 17:37

anyhow.. my question is... on the basics of less pressure = longer heat up times but more grip.. more pressure = shorter heap up times but less grip.. (getting really laymans here)

Someone feel free to tell me I'm a tit........ but - Lower pressure generates MORE heat due to tyre flex, I'd assumed that it also means the tyre heats up quicker, no? Lower pressure does give more grip, unless so much heat is generated that it goes off.
You need to bear in mind that in the wet, if you lower the pressures too much to generate more heat that you effectively squeeze up the tread which means the water isn't able to disapate effectively.
In the dry if you're runing at 30psi cold, check pressures after a session. 10-15% rise is good. ie <32psi, not getting hot enough so drop pressure. Above 35psi, too hot, add some more air.
Race tyres are a different animal so post up here again if you start using them

**Mishy** · 6th August 2010, 20:50

ok, so there are a few things to keep in mind here.

One - manufacturers reccomended pressures for the purpose intended - this is the best base pressure to begin with.

Two - lower pressures do several things. Firstly, there will be a more significant gain in temperature, and possibly pressure with a lower starting pressure - especially if you are not using warmers, but there are pitfalls to going too low - especially on the front tyre.
On the front, be wary of letting too much pressure out, as a tyre that is underpressured will struggle to turn in, and then tend to fold once it gets turning.
The rear can benefit from a lower pressure than the front ( Conti Race Attack Comp. is 31psi front hot, and 27 rear hot) , as you can take adventage of a larger contact patch which gives more side grip that comes from a lower pressure without the lack of support issues that the front tyre has with steering the bike.

As a rule, you should look for certain increases in pressure from your start point, and this will differ depending on whether you use warmers or not.
Look for an increase of about 3 psi from cold in the front, and closer to double that in the rear, assuming that you don't have warmers.
Bear in mind that track day tyres and street tyres will need more pressure than race tyres, as the carcase will generally be weaker, and require more support in the way of air pressure.
If you have warmers, then start by over pressuring the tyre, and then set pressures after one hour or so on the warmer. It's best to let air out, not put cold air in.
Mostly, there will only be a small increase from the "off warmers" pressure to a hot off the track pressure - perhaps as little as 1 psi, so checking and making notes is important to start with.

Having a good base to start from (manufacturers reccomendation) is key, and then a little measuring and experimenting to find optimum FOR YOU is the ticket.

You will soon get a feel for how the track and ambient temp affect the pressures for different days.

**Shaun** · 6th August 2010, 21:56

[QUOTE=Mishy;1129830063]ok, so there are a few things to keep in mind here.

One - manufacturers reccomended pressures for the purpose intended - this is the best base pressure to begin with.

Very Very well said that man. To many think that 30psi in one is good enough for all, and the other terrible thing I hear a lot is, the BIKE SHOP set my pressures, THEY DID AT THAT, but to the reccomended PSI for the Tyres there bike left the factory with

The do.

**lostinflyz** · 6th August 2010, 22:20

deformation = movement = heat

basically the body or carcass of the tyre deforms more with lower pressure (i.e. when you have a flat on your car its not to hard to get your tyre to start smoking). That being said a tyre with tread blocks (wets very much and treaded tyres, less so with sport tyres with very large tread blocks) work on the tread blocks moving to generate heat, thus a lower pressure will force the tyre body to move more than the blocks, thus generating less heat.

Generally in colder conditions lower pressures are ideal, as your likely to generate more heat in a standard supersport tyre as the tyre body will be more flexy, but the inverse holds true (somewhat) of wets where a stiff tyre body can promote movement of the tread blocks, thus higher grip.

If you've you have ever ridden on wets (particularly front) with low pressures they feel like absolute junk.

anyway thats just a lesson in physics, in reality you have to try everything to get an idea of whats good and bad. I suggest moving to invercargill for winter.

**manxkiwi** · 7th August 2010, 10:30

Anyone know where to find the tyre manufacturers pressures? I've looked on the Pirelli and Michie sites and can't find anything! I'm running Road 2ct's and Power 2ct's. I've often thought, surely the same tyre on a different bike would require a different pressure? So are there enormous charts available for a certain tyre on every possible bike? A 180 rear is a common size for heaps of different types of bike, surely they're not all the same pressure?

Anyway, a link would be awesome if someone can help, Cheers..

**cowboyz** · 7th August 2010, 10:48

Originally Posted by Mishy

ok, so there are a few things to keep in mind here.

One - manufacturers reccomended pressures for the purpose intended - this is the best base pressure to begin with.

Two - lower pressures do several things. Firstly, there will be a more significant gain in temperature, and possibly pressure with a lower starting pressure - especially if you are not using warmers, but there are pitfalls to going too low - especially on the front tyre.
On the front, be wary of letting too much pressure out, as a tyre that is underpressured will struggle to turn in, and then tend to fold once it gets turning.
The rear can benefit from a lower pressure than the front ( Conti Race Attack Comp. is 31psi front hot, and 27 rear hot) , as you can take adventage of a larger contact patch which gives more side grip that comes from a lower pressure without the lack of support issues that the front tyre has with steering the bike.

As a rule, you should look for certain increases in pressure from your start point, and this will differ depending on whether you use warmers or not.
Look for an increase of about 3 psi from cold in the front, and closer to double that in the rear, assuming that you don't have warmers.
Bear in mind that track day tyres and street tyres will need more pressure than race tyres, as the carcase will generally be weaker, and require more support in the way of air pressure.
If you have warmers, then start by over pressuring the tyre, and then set pressures after one hour or so on the warmer. It's best to let air out, not put cold air in.
Mostly, there will only be a small increase from the "off warmers" pressure to a hot off the track pressure - perhaps as little as 1 psi, so checking and making notes is important to start with.

Having a good base to start from (manufacturers reccomendation) is key, and then a little measuring and experimenting to find optimum FOR YOU is the ticket.

You will soon get a feel for how the track and ambient temp affect the pressures for different days.

cheers.. that kinda makes sense. I think at the momnet Ill leave it at 30/30 which is working for me but will do some testing on the day to see what happens. I still have to go get a working tyre guage too! (ill be rushing off on Fri to get one as I would hvae forgotten about it all week but hey...)

**cowboyz** · 7th August 2010, 10:49

[QUOTE=Shaun;1129830131]

Originally Posted by Mishy

ok, so there are a few things to keep in mind here.

One - manufacturers reccomended pressures for the purpose intended - this is the best base pressure to begin with.

Very Very well said that man. To many think that 30psi in one is good enough for all, and the other terrible thing I hear a lot is, the BIKE SHOP set my pressures, THEY DID AT THAT, but to the reccomended PSI for the Tyres there bike left the factory with

The do.

im just not smart enough to work out what you trying to say here........