The great wet-asphalt debate

[dmp221]

Two of my biking friends are having a friendly discussion about riding on wet pavement.

My one friend says that a narrow-profile tire has the advantage because it needs to displace less water in order to find it's contact patch.  

The other buddy says bunk-o.  All things being equal (like tread design, tire materials, etc.), a wider tire will always have more contact patch than a narrow one, thus is the better choice in rain.
                                 :dunno:                  

I say there are many times I wouldn't mind sending them BOTH out in the rain to do a study.                    

There is some  beer  and bragging rights riding on this.  Opinions, friends?

[Cal Price]

A guy I know who is an instructor/advanced biker says it don't matter a damn. He recons that with a bikes you have so little rubber on the road that issues like aquaplaning etc just don't apply....Cheery soul!

[Rema1000]

This was always hotly debated on the rec.bicycles.tech newsgroup.  The definitive posting came from Jobst Brandt, long-time poster and alpine cyclist, who also used to engineer for Porsche.  His claim was that hydroplaning can occur when the speed of the vehicle is high enough, and the pounds per square inch on the contact patch is low enough.  He did a spreadsheet showing the speeds needed to achieve hydroplaning, given the expected contact patch sizes and weight of a range of vehicles.  The conclusion was that the family car was the only vehicle which would hydroplane at it's expected speed... I think a fighter-jet taking-off was also on the list as a possible hydroplaner.  But bicycles, motorcycles, semi trailers, etc. all had sufficient weight relative to their contact patch size and expected speeds.

So his conclusion (paraphrased):  hydroplaning is a car thing.

[KevinC]

The racers don't switch to narrower tires in the rain, just soft compounds with lots of water channels and blocks for edges.

Of course changing tire widths might screw up their chassis settings so bad they couldn't tune for the narrower tires. They do adjust the suspension pretty extensivley for the wet, so I imagine if narrow tires were an advantage, they would be using them.

[john]

Well that answers that.

[glenn9171]

Unless you are really hauling ass in deep standing water, a motorcycle should not be hydroplaning...assuming the tires have sufficient grooves left in them.  The front tire seems like it would take most of the action anyway, if you are travelling in a straight line.  Tire width would not make much difference as you don't gain much actual tread footprint with a wider front tire.  I don't think it would make much difference either way in real world applications.  Due to lack of vision, retarded cagers, etc., it's best to keep things sane in the rain anyway.