Riding in the Wet. Advice.

[icenian]

Why would you think I mean that?

Because you said they'd grip at ambient temperature. Which is about -15 to 40 in the UK, though of course more typically -5 to +30.

Of course road tyres will behave differently across a 55 degree range but that's not what's being discussed here is it?

Well yes, and quite explicitly too. OK the 55 degrees is a bit cheeky but it's true for the more realistic range of 30 something.

What I said was that road tyres do not need heat in them to grip in the wet.

If you mean, they aren't entirely frictionless at ambient temperature, clearly you're right, but that would be a trival remark and I wouldn't accuse you of meaning that.
It's reasonable to infer (and therefore reasonable to seek clarification) that you meant they didn't offer any more grip when warmed up. Also you suggested that they wouldn't reach a temperature above ambient.

It's an interesting proposition, and there's wet road out there, so I'll see if my tyres warm up when I ride home!

[sproggy]

Because you said they'd grip at ambient temperature. Which is about -15 to 40 in the UK, though of course more typically -5 to +30.

Yes, but the discussion here is about how tyres behave in the rain, not how their behaviour differs at different ambient temperatures. I said that tyres will grip well (unless you've got Deathwings ) in the wet at ambient temperature without being warmed up by riding, and that's true regardless of whether the ambient temperature is (given normal UK rainy conditions) a bit above freezing or mid-20s.

It's reasonable to infer (and therefore reasonable to seek clarification) that you meant they didn't offer any more grip when warmed up. Also you suggested that they wouldn't reach a temperature above ambient.

It's an interesting proposition, and there's wet road out there, so I'll see if my tyres warm up when I ride home!

Yes, I meant that they won't offer any more grip in the wet when warmed up, mainly because they won't warm up significantly due to the water taking the heat away. This is why racing bikes/cars on full wets on a drying track will tend to stay on a wet line on the straights to cool their tyres. Different in many ways, I admit, but it demonstrates the effect of tyres being cooled by wet surfaces.

I suspect (hope?) that most of us, whether we care to admit it or not, leave enough of a safety margin in the wet not to be able to put this to the grip test. However if it's wet (really wet - not just damp!) when you ride home I think you'll find that your tyres are not noticeably warmer when you arrive than when you left. Particularly if you ride like someone who's never ridden in the rain before!

[Dilbert]

Yes, I meant that they won't offer any more grip in the wet when warmed up, mainly because they won't warm up significantly due to the water taking the heat away. This is why racing bikes/cars on full wets on a drying track will tend to stay on a wet line on the straights to cool their tyres. Different in many ways, I admit, but it demonstrates the effect of tyres being cooled by wet surfaces.

I suspect (hope?) that most of us, whether we care to admit it or not, leave enough of a safety margin in the wet not to be able to put this to the grip test. However if it's wet (really wet - not just damp!) when you ride home I think you'll find that your tyres are not noticeably warmer when you arrive than when you left. Particularly if you ride like someone who's never ridden in the rain before!

Right on the money, unless you're running slicks in July the tyres won't warm up to the same degree that racing tyres do, completely different rubber compounds, we ain't Ron Haslam doin' testing for Honda

[Alba]

rain-x for the visor is well worth it.

[icenian]

if it's wet (really wet - not just damp!) when you ride home I think you'll find that your tyres are not noticeably warmer when you arrive than when you left

OK, that's a testable hypothesis! At least, it will be when it starts raining again.

I'm genuinely interested you know, since you may well be right and if so I'd like to know it, but getting at the facts requires skeptical enquiry...

With regard to racing tyres, they certainly won't warm up on the road (in any reasonable use in normal conditions), but the manufacturers say that road tyres are built to warm up more easily. I'm not clear though to what extent that's because they generate more heat, or because a given amount of heat causes greater warming (by "warming" I mean a rise in temperature, not the heat in the tyre). I can see that construction and especially tread could affect heat generation, but I suppose thermal capacity might also vary depend on the materials (don't know if different rubber compounds vary in thermal capacity but I guess the other materials in a tyre may do so; don't they claim steel is some radials dissipates heat???).

Doubtless someone on the tyre industry will be along in a minute

Incidentally, my actual feeling about riding in the wet (or the dry) are that I'm not too bothered about the theoretical grip of a tyre, as in reality lack of grip usually becomes an issue because of diesel, gravel or whatever. If I fitted super grippy sports tyres (and managed to run them hot enough to work), it'd probably mean I would just get the capacity to be going 20mph faster at the point an enormous cow pat on the apex rendered them as useful as a pair of Roadrunner remoulds Which is just a good reason not to do it. I cannot imagine actually running out of the grip offered by "touring" tyres when riding in good conditions.

[Wee Jack]

OK, that's a testable hypothesis! At least, it will be when it starts raining again.

When I was doing my advanced training on a Pan-European and was being encouraged by my Police Instructor to "make progress" we would often finish a 10 mile twisty section in POURING!!! rain , and while I was being de-briefed, the bikes would be sitting at the side of the road will steam coming off the tyres, and they were warm to the touch, more on the intructors bike than mine , but they (by nature of the job) move around a bit more on the road to observe what the student is doing with gears and clutch etc and him being a rozzer was about twice the weight of wee me !!!!.

Long winded but - Yes, tyres do get hot in the wet - when your pushing on.

[Steve C]

Yeah, Wee Jack, I thought I remember taking note of the heat on my (front especially) tyres after a wet ride home

And I'm not really a making progress kind of rider...

[Dilbert]

Yes obviously they will warm up a bit, heat is generated due to the rubber flexing as it rubs along the road, go faster it gets hotter and I dare say if you're really "making progress" there will be a reasonable amount of heat, but, nothing like the same as when it's dry and sunny.

Don't know about steel in radials cooling a tyre I would expect it to slow the heating of a tyre, but then retain and build the heat more?

No, tread makes very little difference other than a slick (clever name for a bald tyre) will have more surface area in contact with the road (unless that's what you meant) the heat is caused by the rubber molecules rubbing against each other (they get excited) in a softer compound the rubber flexes more and the molecules move round more rubbing more other molecules, this increases with speed, so if you stopped Rossi after a 200mph straight and touched his tyres you would need to go to A&E, if you've been plodding about in the rain at low speeds (and depending on how cold the rain and the road is) then you won't be in any danger of frying an egg on them

Anyhoo having said all that, yes the biggest problem with riding in the wet is that it re-invigorates the diesel/ oil/ tyre rubber on the road and makes for slippy $h1t, which is odd because cow$h1t gets the slippyness washed out, unfortunately doesn't work as well on horse$h1t and there's lots of that about round here

[Lord Vader]

p.s. in his usual flipant way Mudwiz has a point (well hidden though) try and get some practice in off road, lots of racer types do this as it helps refine your control and makes you worry less about those little slides.

Listen guys i know nothing about riding.I have got no advance rider or anything but i think you are getting a bit side tracked and just going to confuse a guy which is new to bikes full stop.
I really think that the advice to go off road is one of the best here.I am not talking serious stuff or anything.Maybe a little mud where you can feel the rear sliding that sort of thing.
It did help me a lot.Because i used to freak out on the bike whenever i went over a manhole cover or a white stripe in the wet and the bike did his little"twitch" thing.
It improves your balance at speeds where you can not damage your bike to much if you are unlucky.Most of the time you just pick you bike up and carry on.Alone the experience to drop your bike will help as it will take the Paranoia out of you to a certain extend.

[sproggy]

When I was doing my advanced training on a Pan-European and was being encouraged by my Police Instructor to "make progress" we would often finish a 10 mile twisty section in POURING!!! rain , and while I was being de-briefed, the bikes would be sitting at the side of the road will steam coming off the tyres, and they were warm to the touch, more on the intructors bike than mine , but they (by nature of the job) move around a bit more on the road to observe what the student is doing with gears and clutch etc and him being a rozzer was about twice the weight of wee me !!!!.

Long winded but - Yes, tyres do get hot in the wet - when your pushing on.

The other factor you didn't mention is combined bike/rider weight. More weight will mean the tyres are working harder and therefore more able to generate/retain heat than on a lighter bike. And a fully-equipped police Pan is NOT a light bike. Come to that, a normal Pan isn't either.......

Obviously the type of road plays a big role too. When I arrived at work this morning after my usual 'enthusiastic' ride into North London the tyres felt the same temperature as the footrest rubbers. Cold. That was on mainly dry roads but in town you just can't (sensibly) work the tyres hard enough consistently enough to build up heat. But on a heavy bike on fast, twisty roads the situation could be very different.

But I still maintain that the amount of heat you can buld up in a road tyre in the rain will make little, if any, appreciable difference to its wet grip.