Wet weather tyre pressures?

[Rodeo Ron]

With the prospect of wet weather looming over the autumn / winter (or have I missed something) the question of tyre grip climbs a rung or two. So the question is: Is there any advantage in changing normal day to day tyre pressures in the pursuit of extra grip? I have read conflicting advice. On the one hand a reduction in pressure of a couple or more pounds pressure should increase tyre temps, but does this increase grip in the wet? On the other hand an increase in pressure of a pound or two preserves the tyre profile, reduces the contact area, and therefore gives greater penetration of the reduced contact patch through standing or sheeting water! Were do we go with this, does any boby have an educated or experiential view?

 

[karnevil]

Why do people always want to mess with tyre pressures?
Tyre manufacturers and vehicle manufacturers spend millions testing just do as they suggest at least then when and if you have an accident the Police/Insurance investigators cannot say tyre pressures were a contributing factor.
I used to let a few PSI out of my car tyres for PCT's yes one gained a bit more grip but this was only at low speeds and on mud and grass no advantage at all on the road unless one is travelling on thick snow.

Leting a few PSI out of your bike tyre will make the handling awfull putting an extra few in will just make em wear more/wrong then they are fecked for when they are returned to normal.

Get a decent pressure gauge and stick to recommendations.

Pointless exercise IMHO.

 

[davegs]

Tyres

If your looking for an accident lower the pressures if not leave them alone, check them regualy and keep to the pressures in your owners manual!. It's there to be read and obeyed! Lowering pressures is a specialised thing for off roading mud and such like but NOT for amatures or road use. If you want a second opinion contact your tyre manufactuer but other wise leave them alone!. We have enough bikes having accidents with out trying!.
Dave GS.

 

[Pukmeister]

Wet weather riding

Your tyres are fine on standard pressures (36/42).

Relax. Literally.

I crashed my GS recently on a wet road for the first time in 4 years of ownership, despite having ridden in some awful conditions over the years.

In hindsight I was tense, riding too fast without thinking, and simply exceeded the maximum amount of grip that my front tyre could provide when leant over.

If I had relaxed a little, ridden smoothly and entered the corner a couple of MPH slower, and maybe used a degree less lean I'd have been fine.

EDIT: Best thing to do is fit some quality engine bars just in case - I'm glad I did!

 

[The Bede]

... Reduced pressures cause the tyre to deform excessively which constricts the sipes (the gaps between the tread blocks) reducing the tyre's ability to clear water and hence reducing grip levels in the wet

... Excess pressure will reduce the tyre's ability to flex, within it's design limits, under load. The lack of 'micro-flex' can cause the tyre to give up it's grip the more it is pushed.

... As the assembled have suggested, leave the pressures as standard.

 

[Slowdown]

Rodeo Ron - You must of heard that stuff from tyre 'expert' who's a complete cowboy.

As others have said - the manufacturers state the recommended levels after much testing and a seriously vast amount of money. Why would you possibly think you could do better???

 

[colinw]

Just to be different, I run my pressures 2psi below recommended in the manual, this gives me a better winter temp on the tyres and is not enough to cause any issues as raised above, you will hear the "track boys" talikng of lowering the presure on a wet day to increase temp and allow more grip but they drop to as low as 25psi, you don't want to be doing that but 2 psi will give you an improvement.

 

[Arsey]

With the prospect of wet weather looming over the autumn / winter (or have I missed something) the question of tyre grip climbs a rung or two. So the question is: Is there any advantage in changing normal day to day tyre pressures in the pursuit of extra grip? I have read conflicting advice. On the one hand a reduction in pressure of a couple or more pounds pressure should increase tyre temps, but does this increase grip in the wet? On the other hand an increase in pressure of a pound or two preserves the tyre profile, reduces the contact area, and therefore gives greater penetration of the reduced contact patch through standing or sheeting water! Were do we go with this, does any boby have an educated or experiential view?

Leave your tyre pressures alone.

The biggest advantage to obtaining more grip in the wet winter conditions is to make sure you have the specified winter oil in the bike.


Check your handbook for details or send a PM to an expert such as tarka to help you.

 

[SilverFish]

... constricts the sipes (

I now cant wait until I can use that expression in conversation...

 

[pablo666]

Leave your tyre pressures alone.

The biggest advantage to obtaining more grip in the wet winter conditions is to make sure you have the specified winter oil in the bike.


Check your handbook for details or send a PM to an expert such as tarka to help you.

You Bastid !

 

[Rodeo Ron]

Just loving the replies

I'm just loving your replies - keep em coming, be them superficial or useful. Just a thought- If you slavishly go by the book, a 20 stone solo rider, needs lower pressures than an 11 stone pilot with a 9 stone pillion?

 

[Funners]

Just to be different, I run my pressures 2psi below recommended in the manual, this gives me a better winter temp on the tyres and is not enough to cause any issues as raised above, you will hear the "track boys" talikng of lowering the presure on a wet day to increase temp and allow more grip but they drop to as low as 25psi, you don't want to be doing that but 2 psi will give you an improvement.

Yes but..thats cos track pressures on the whole are lower than road ones as the resulting higher temps of track use push them back up to where they should be !
as stated previously..Wet tyres do not respond well to lower pressures as they close the treads up and/or overheat...
for road use..std is fine..

 

[STUBBS]

I'm just loving your replies - keep em coming, be them superficial or useful. Just a thought- If you slavishly go by the book, a 20 stone solo rider, needs lower pressures than an 11 stone pilot with a 9 stone pillion?

its all about averages they dont give any weight limits for 2 up riding or fully laiden

 

[Rodeo Ron]

its all about averages they dont give any weight limits for 2 up riding or fully laiden

Agreed, averages and compromises distilled from a wider envelope of data. Of course the book burning society wouldn't want the wider data released just in case we all became better informed - God forbid

 

[karnevil]

Agreed, averages and compromises distilled from a wider envelope of data. Of course the book burning society wouldn't want the wider data released just in case we all became better informed - God forbid

Yes and the manufacturers have that wider envelope,they have explored all the averages and compromises and released that wider data so we are better informed and printed it in owners manuals,so we become better informed they even,nowadays,have the info on web sites so that should we accidently burn our books the information is still available so we dont have to make it up and get it wrong- God forbid

 

[Wapping]

Agreed, averages and compromises distilled from a wider envelope of data. Of course the book burning society wouldn't want the wider data released just in case we all became better informed - God forbid

So - to follow your 'The devil is in the detail' response - why did you ask the question without telling us how much you weighed and / or neglected to tell us how much your over stuffed pillion weighed?

It's just a nobby question in the first place.

Wet or dry. Try riding your bike with the tyre pressures recomended by the tyre / motorbike manufacturer. Check with them if you are unsure what pressures these should be. If you like them, fine. If not change them. Play around, after all it's your bike whether it is in the wet or the dry. Run them at 25 or 50 psi for all we care.

Failing that, get some training as to how to ride in the wet, without worrying about two or three psi.

 

[colinw]

Yes but..thats cos track pressures on the whole are lower than road ones as the resulting higher temps of track use push them back up to where they should be !
as stated previously..Wet tyres do not respond well to lower pressures as they close the treads up and/or overheat...
for road use..std is fine..

Yep I agree, thats why I said "you don't want to be doing that" but I run 2psi lower than book because it allows the tyre to grip the road better on cold tarmac as it flexes just slightly more. JMO but it works for me, don't knock it till you try it !!

 

[Nate]

i think the three tip top tips from me would be...

1) let the tyres warm up... and at the same time, let your self warm up

2) keep warm and keep relaxed... amazing how a bit of cold stops you moving around on the bike.... and if you can't waggle your elbows in a corner, your too tense

3) Just get used to riding the damn bike in the wet... its amazing how much modern tyres will grip...

I left a bike event this year and it was pissing down... came up behind a large gaggle of bikes all doing 40mph (it was in a 60)

So, after getting bored stuck behind them, proceeded to (ahem) make a bit of progress... got to the front of the queue expecting a tractor or something... Nothing... zip, nil... just 30 bikes (mostly sports bikes) doing no more than 40 cos it was wet...

 

[Bem]

gives greater penetration of the reduced contact patch



This has to be the funniest thread in ages - keep it up!

 

[Gipsy]

I agree wholeheartedly with those who have posted and confirmed that it's best to run at the pressures recommended by the tyre manufacturers. I would however point out that on track when tyre pressures are altered it is in the attempt to get the desired air pressure in the tyre when actually at running temperature in the race. Hence at high speeds or in high temperatures ( both conditions which are likely to increase the air pressure in the tyre ) the starting pressure in the tyre may be lowered so that when operational the pressure is at the optimal level.
Just to confirm that it isn't an area in which to dabble without specific knowledge, all high level racers ( motogp superbike etc. ) will have a tyre technician whose sole job is to help with tyre choice and pressures. Also at the California Superbike School a tyre technician will advise on appropriate pressures for the day, but will also ensure pressures are returned to normal before leaving to ride home.