Wider tyre in the wet?

[djones]

Is a wider tyre still better to have in the wet?

I don't know how this randomly came into my head but I remember reading a tyre review and they were doing two different groups of test.

One was a premium car with say 245 width premium tyres and the other was a small hatch with say 175 basic tyres.

In the dry the wider tyres were much better at something like braking but in the wet there was hardly anything in it, indeed on the aquaplaning test the small tyre won it!!

So is it an advantage to have a wider tyre in the wet all things been equal and within reason?

[machin]

I believe that narrower tyres are generally conceived to be better in conditions where there is standing water as the narrower width forces the tyre down onto the tarmac beneath (more pressure) thus reducing aqua-planing as your article confirms.

Also Rally cars use very narrow tyres in the snow to help them compact the snow into a more grippy surface (again, more pressure with narrower tyres).

[Fil]

Good question! This is tailor-made for Jersey Tom..

I was always fascinated during the tyre war, just how vastly different the tread patterns were between Bridgestone & Michelin - seemed like 2 polar philosophies on how to deal with dispersing water.

I assume this is what the crux of the answer is.. a suitably matched tread pattern for tyre width to allow enough movement of water.

as long as you can move the water, the larger the contact patch the better usually..

Jersey..? [-o<

[xpensive]

In 1971, there was a Formula 2 race at Tulln-Langenlebarn in Austria, where the track was actually an old military airfield, why the surface was xtremely flat. Come sunday, the rain was coming down in buckets and the flat track was covered with water and drivers were spinning on the straights even on wets, why most cars ran the race on four front-wheels.

Not Japanese hero Tetsu Ikuzawa, he ran on Formula Ford rims with Firestone Torino tyres! Made 6th in the second heat.

[Giblet]

I know it's just a video game, PGR4 on Xbox Live, but I did a wet race once in a game of "cat and mouse", where the cars have damage turned off, and a whole field of class A cars (Zondas, Lambos, Aero TT's, etc) are trying to run a D class car off the road, which was me in a Maerati 250F. The event was rain soaked.

The pizza cutter wheels allowed me to drive off in the distance much the dismay of all the cats.

[Jersey Tom]

Wider tires aren't always the best option in the dry (though generally its good)...

I dunno. I don't have much experience with rain race tires.

[marcush.]

this surely is a question of quantity of water coming down amount of water that will be soaked up by the surface without creating puddles -effecting track draining- to
mention a few variables in this question.
If the water is not too much you will be able to get away with hot slicks remarkably well ,but at some point of water standing you really need to create big draining passages into the tyre itself to get rid of the water to avoid aquaplaning ,simple as that.
The trick is not to create wide sections of tyre surface where water cannot escape .

[Giblet]

From what I've read they are basically pumps that happen to be attached to an F1 car. I would think if the tread was the same, and scaled accordingly, a thinner tire would tend to aquaplane less, but other than a downpour, I'm not sure if wider is better or not.

I would think in damp conditions there is no aquaplaning and it would start to get complicated.

[Ciro Pabón]

Well, I'm positive that longer (thus thinner) tyres are better in the wet. I think they really pump the water better. I really like to kart in the wet and it rains heavily around my place, so I'm not sure about the theory, that's the feeling I have.

However, this is very clear when you drive construction machinery: when the motorgrader still has grip, the loader hasn't.

For those not used to drive heavy machinery, a motorgrader has higher, thinner wheels (to be driven primarily on dirt roads), while a loader has wider, "shorter" tyres, more or less like balloons (to be used in quarries, where you don't want a high pressure on crushed rocks, to avoid punctures).

It is quite dangerous to underinflate a loader and drive it in the wet: as you can imagine, grip is essential in that kind of vehicle. If you don't have grip, you cannot "pick" the material, because the bucket won't "penetrate" the gravel or whatever you're loading. I bumped into a couple of trucks when I drove a loader for the first time on the wet. BTW, this is almost as entertaining as racing...

Motorgrader: good in the rain, thin tyres


Loader: bad doggie (in the rain), wider tyres


I'm not totally sure if this can be applied to racing cars, where speeds are (duh) higher. Even taking that in account, a construction vehicle that is "unbalanced" has lower grip. When you load the bucket, the rear wheels slip easily, so, in the rain you try to load "at once". It's very difficult to complete a partial load, because, once you've loaded partially the bucket, you lose the ability to push into the material you're loading. This doesn't happen in motorgraders, which have the cutting blade more or less in the middle of the machine.

I'm also positive that if the pressure is low (no matter the width of the tyre) you have lower grip, because (I imagine) the tread becomes convex, so it's easier to accumulate water in the "arch" under the patch. This is evident when you drive an underinflated kart.

Actually, I put a couple of extra psi on the tyres in the rain, I'm not sure if this is wise, but it works for me. I also try to steer harder in the rain (altough it doesn't seem logical at first sight): the tyres seem to "bite" better. When you do that you have to be very careful not to touch the ruts (I mean, any channel where water accumulates): if you do that, the kart will lose all the "extra" steering power and you will hydroplane.

I think that's the reason why it's harder to lose grip on a motorcycle: the tyres are "rounded" and thin. I mean, the cross-section of the tyre is rounded (all tyres are round, of course ).

[WhiteBlue]

I think that's the reason why it's harder to lose grip on a motorcycle: the tyres are "rounded" and thin. I mean, the cross-section of the tyre is rounded (all tyres are round, of course ).

There are ways to loose grip with a motocycle very badly. I remember an episode from the 80ties when I had no car but a single cylinder Yamaha SR500 motorcycle.




I drove into town from my flat (out in the back country) in summer. It had not rained for 6 weeks or so. This was actually in a city with hilly terrain. When I came down a gently sloped road it had started to rain but not like from buckets more like a drizzle that wetted the whole road without creating running water. I was approaching a red traffic light some 300 m away. I remember that I thought "Hey, apply those brakes gently it is getting wet."

I only touched the the brake ever so slightly and found myself sliding on the backside with with my bike for an endless slide of almost 50-70 m. I only had a pair of jeans on and no leather trousers which I would usually wear. I was surprised that I did not hurt and thought the shock was preventing it. When I came to the end of the slide after what felt like an endless time I got up and looked at the damage. I was practically unhurt and my jeans were not even torn. The ashalt surface of the road felt as if it had been covered in soft soap. Apparently the small amount of water had wetted a film of dust that was deposited over several weeks by the traffic and had created a slimy film on the road. I never experienced thast phenomenon again but I keep thinking about it when I drive on wet surfaces in summer.

[gator]

I drove into town from my flat (out in the back country) in summer. It had not rained for 6 weeks or so. This was actually in a city with hilly terrain. When I came down a gently sloped road it had started to rain but not like from buckets more like a drizzle that wetted the whole road without creating running water. I was approaching a red traffic light some 300 m away. I remember that I thought "Hey, apply those brakes gently it is getting wet."

I only touched the the brake ever so slightly and found myself sliding on the backside with with my bike for an endless slide of almost 50-70 m. I only had a pair of jeans on and no leather trousers which I would usually wear. I was surprised that I did not hurt and thought the shock was preventing it. When I came to the end of the slide after what felt like an endless time I got up and looked at the damage. I was practically unhurt and my jeans were not even torn. The ashalt surface of the road felt as if it had been covered in soft soap. Apparently the small amount of water had wetted a film of dust that was deposited over several weeks by the traffic and had created a slimy film on the road. I never experienced thast phenomenon again but I keep thinking about it when I drive on wet surfaces in summer.

Here in Florida it tends to rain frequently, and it is more apparent when it hasn't rained in a while like you were saying, but the first part of a rain storm is the most dangerous to drive in because all the oil and other junk on the roads hasn't had a chance to wash away into the gutters. I would much rather drive in hurricane type rain than a sprinkle for just this reason.


My experience has been that racing in the rain is mostly about tread pattern and compound selection as I have never had the option to run "wider rain tires". My guess would be that the thinner ones would be less prone to aqua-planing when compared to wider tires with the same tread pattern. But then again, if water isn't standing i would pick the wider tires. Also, for my type of race where the green never drops in a heavy storm, the track tends to dry out as the race progresses. So in my case I would pick the wider, hardest "rain" compound I could find to have some tire life left at the end of a race.

Cool question and one that I had never thought about before, thanks for sharing!

[gator]

Actually, I put a couple of extra psi on the tyres in the rain, I'm not sure if this is wise, but it works for me. I also try to steer harder in the rain (altough it doesn't seem logical at first sight): the tyres seem to "bite" better.

almost forgot...

I agree in putting more air pressure in for rain tires. Think about it, the tires aren't generating as much heat, so the water in the air inside the tires can't expand and increase the tire PSI. This is why test sessions in the wet are great every once in awhile. Also in the wet (doesn't apply to carts since they have no suspension) I disconnect all sway bars to try and get as much weight transfer as possible, so it does make sense to "throw" a car into a turn which helps in weight transfer and extra traction on the outside front to aid in turn-in.

One last thing, if your series allow it, I HIGHLY suggest running nitrogen in your tires. It takes a lot of guess work out of setup due to changing track conditions. Tire PSI does still fluctuate, but less than straight air.
That or tire PSI bleed valves...

[Jersey Tom]

That or tire PSI bleed valves like NASCAR runs...

Not used in NASCAR.

[marcush.]

sideline about running on gravel:a friend of mine did top level rally sports in the late s early 80s with a 911 in Germany and France.back then Gravel was very common in rallying ,not like todays all tarmac events.
He found out that wide tyres were a lot faster then those blade type gravel tyres that you normally find in the sport and they came to their home event well prepared
for those gravel stages and blew away all gravel specialists on the famous Rally -Vorderpfalz- on these stages....
so as there are different types of gravel and dirt ,there is also different reaction coming from the underground when driving over it in anger...

[gator]

That or tire PSI bleed valves like NASCAR runs...

Not used in NASCAR.

I stand corrected, thank you.