Thoughts on tyre pressures in the wet
 

I've been thinking about tyre pressures, and what's best to run in the wet. Both my offs this year have been on wet tracks, and both went the same way, instant loss of front traction and down so fast I don't even remember what happened.
Now usually I run 29/29 in dry on a warm day, I increased this to 31/32 for donny qualifying as it was wet, and I'm wondering if this contributed to my fall. Up until that moment the front end had felt fine, back had slid under moderate power exiting macleans a couple of times but that was it.
So, I thought it might be interesting to conduct a poll of those who fell in qualifying, to see what tyre pressures they were running, and the same for those who managed not to fall, and see if any trend emerges?

I'll start -
31F/32R - lost front, lap 5.

I run 30/30, rain, sun, snow, wind.

;)

32F/30R - Qualified 8th overall, 2nd in class.

Show off ;)

:D

dry track: 2.1bar front / 1.9bar rear :D
wet track: I stay home.

Are you sure it's not Joe.1 Bar front and rear :D

:lol:

Whatever tyre you run - you should run higher pressures in the wet for two reasons:


1. To keep the tread apart/open so it can do its job of removing water.
2. The tyre is running cooler in the wet and is therefore at a lower pressure anyway. This causes the carcass deflects more - leaving it out of shape/profile.

I'm fairly tempted to do that too from now on, this is starting to hurt!!!

Thats the principle I work on

My Dry pressures are normally 31F/30R unless its a very hot day or if I'm using tyre warmers then I usually run 30F/29R

30F/30R with no problems cornering in the wet, even at my lean angles,
..until you go off the treaded part of the front tyre in the wet at Paddock Hill bend :devil:

Did I mention that I crashed at the first corner?

at cadwell on friday i run 31f 29r in the dry.... in the wet and it was ****ing it down i rode with 32f 32r

I think mine are 31psi front and rear all the time. Should probably check now and again really!

thats the spirit!

i honestly think for most people in DD its a confidence thing. if someone changed all our pressures by 2 psi how many of us would come in and go: 'somethings not right with the bike, it felt really odd, couldn't get the power on, get it to hold a line etc' ?

i up my pressure 1 psi in the wet. do i notice the difference? of course not. does it make me quicker?, doubt it. but i go out there feeling the bike is set up right for the conditions so mentally it helps.

I run approx 29/29 in the dry and approx 31/31 in the wet
Tim

just ride.! as long as they are in the 30 range,>!

We have so few variables that we can "fiddle" with on the DD bikes, its great to mess with something ;)

And as its the only regular contact point with the track, any grip that can be gained through correct tyre pressures has gotta be good.

You won't mind me setting yours to 39/39 then?

;)

I ran 30F 32R all day ...
meant to run 30F/30R in the dry race but forgot

i need the challenge..................

ok between 29.5 and 31.0.....................does it really make a difference.!...i doubt it when u stake in track temp variable, tyre gauge variables..etc..

With road tyres it doesn't make that much difference - they're designed to work in a wide range of conditions. With race tyres it definitely does matter.

they are road tyres.....just used on a track.?.............

Indeed - so I am saying it probably doesn't make that much difference with the Diablos if you are a couple of psi one way or another. In principle though, you should run slightly higher pressures in the wet for the reasons I outlined

Could run them flat in the wet for all I care :)

Yes. Well we all know:

1. You don't race any longer.
2. You're a shandy-drinking southerner.

;)

Only one of those is correct.

But as to the wet racing, I'm gonna buy the dsc as everyone has their price and I am a billionaire, I'm then gonna ban wet racing.
Remember your wet lap times are directly linked to your IQ so the lower your lap time......., stupid is as stupid does :)

agree on that sire...........

Nottingham is south...a long way south. of here. So you are a southerner in my books.

Re. IQ...I'm ok here....I'm getting more intelligent with age :lol: You should see how SLOW I am these days.

Zimbo:
My thoughts on your post, I could be right I could be wrong - cue Jonny lol

You mention:
" ... instant loss of front traction and down so fast I don't even remember what happened..."

Assuming you're not accidently touching the front brake lever causing the front to wash out, when its wet then the tyres are much closer to letting go due to lack of adhesion, and when you're cranked over entering a corner it wouldn't take much lever pressure to cause this in the wet, and we've all tensed up some point when experiencing a big moment on the track.

Then could it have been after you rolled off the power entering the corner (or even just after this) in which case it maybe down to your front forks being either too hard or too soft ie not very compliant.

How's the balance of your bike at the front when off the power ie when you throttle off at the end of a straight does the front end stay still ie too rigid, or does the front end fall away and you loose the feel of the wheel thru the forks ie too soft, or does it just dip a little but you have confidence in it and can feel what the tyre is doing?

Also whats your engine idle/tickover speed?
1500, 2000, 3000, 4000rppm?
Can you adjust the tickover/fast idle whilst riding the bike (I've put the fast idle lever back on my bike for this reason - eh Tonio lol), try changing this out on track to a setting that helps your front end settle better when getting off the power (mine's ~3000-3500). I find in the wet that the tickover can really help in the balance of the bike off the power, it also helps in the dry but not to the same degree as in the wet.

Cheers
Glenn

P.S Anyone want to buy my bike? lol

As for your donno crash Zimbo I was right behind you. It appeared to me to go down as soon as you hit the front brake, I thought wow he's braking late..........:)

So why do people tend to run higher (or the same) pressures in the front tyre compared to the back on the track, whereas presumably you run higher in the rear on the road?

Don't you?

The answer is simple - more energy input to the rear tyre.

No I wasn't on the brakes at all, was on a neutral throttle and already in the turn. Perhaps I was just getting a bit overconfident and tried carrying too much corner speed through a wet and slippery corner!

Thanks for your thoughts Glenn, in the dry I have no trouble with the front end at all, it's only the second time I've ridden the bike to be fair but tried it on a test afternoon at Mallory and had loads of confidence tipping in to any of the corners, fast or slow, on the brakes or not.

On reflection then, I was probably just trying to go round too quickly . . .

You've just answered the question yourself.

Already in the turn and on a neutral throttle. You'll have loaded the front end rolling off the gas. You can't get away very often doing that in the dry let alone the wet.

From my viewpoint about 20yds behind you didn't make the turn at all, you went in a straight line into the gravel and so did the bike behind you, it really did seem as soon as you hit the brakes you went down, the bike behind did the same but a bit more stylish ;)

I put 35psi in the fuel tank as that is the bit that touches down first in the wet.

HTH

Shouldn't you be emptying nappies? :lol:

;)

You were watching his brake lights again, weren't you? :(

Well, you were in a much better position to see that I was, must have gone down as I went to turn in then I suppose. I'm going to put it down to overconfidence, and try to learn from that - not try to take slippery wet corners too fast in future!

Monica shoulda known better after Paddock Hill :lol: