I'll have to check the tread depth it seems. So what's the softest tyre out there that doesn't compromise on performance?
This question has a profound or 'cheep' answer.
The first part is 'soft tire'. Whether the tire compound is made of soft rubber or not, does not depend on the side wall. All car tires are made of several different rubber compounds.
The layer inside the tire is meant to hold air;
the bead layer surrounding the rim works like a giant O-ring to seal the tire to the rim;
the side wall is made of a different rubber compound;
the central tire tread and the tread edges are also made of different compounds.
So whether the side wall is soft or not, has no bearing on how sticky it is on roads. The stiff side walls are only found on UHP (ultra high performance) tires - it is to improve cornering grip.
The second portion of the answer is regarding what tires works best on wet roads. Maximum traction on wet roads is a function of both hydrodynamic effect, and squeezed film effect.
Hydrodynamic effects comes on above 20km/hr. Hydrodynamic effect does NOT depend on your tire compound. It depends on the road surface, tread design, tire pressure, contact patch shape and water film thickness.
To go fast on wet roads, you need these wheel specifications. It may be counter-intuitive to you, but this the conclusion of many many doctorate and industrial research:
1. narrow tires. Wider tires are actually more slippery on wet roads at high speeds. But many tire shops like to sell you a different vision. Wider tires obviously cost more. More profit is the reason. Safety is NOT the reason.
2. bigger wheel diameter. Bigger overall diameter improves wet grip. However just switching from 15" to 18" rims and tires while maintaining overall wheel diameter does nothing at all.
3. high tire inflation pressure. Many people mistaken this part. They thought reducing tire pressures improves wet grip. Actually its the reverse!
4. presence of transverse and longitudinal grooves on the tread. Another hot and very sensitive topic. Many tire manufacturers advertise their tire compounds as having superior wet grip. However the truth is when hydrodynamic effects take over above 20km/hr, whether your tire compound comes from China or Michelin makes NO difference. The most important thing is the tread design. So if your pirelli PZero allows you to corner at Formula One speeds during a thunderstorm, it has everything to do with advanced tread design - the tire mould design basically.
5. total vehicle weigh is not significant. Heavy or light cars - is not important at all. Again many people think a heavier car will have better grip on super wet roads at high speeds. This topic has been the subject of alot of research many decades ago. The answer is not what you think.
Squeezed film effect works below 20km/hr. This is where tire chemistry makes an impact. Vehicle weight also helps. Squeezed film effects come into play when you travel at slow speeds in a wet MSCP, or on the road. At these speeds, obviously the tread design is not important. Wet (and dry) tire traction comes from the rubber molecules making contact with the road surface.
So if your car use China branded tires, it may have problems with wheel slippage going up a wet slope in say Clementi Mall. Loading it down with more passengers can help improve grip here.
In summary, if you are going above 20km/hr and need to make an emergency brake, please be reminded that your michelins, pirellis, continentals, yokohamas, etc are able to save you because of the tread design, which works best when the tire is almost new. The actual tire compound itself matters little when hydrodynamic effects come into play, except when the specific tire compound was chosen to maintain the shape of the sipes to ensure its ability to channel water away at maximum volumetric efficiency.
Having said that, an emergency brake is supposed to bring you to a FULL stop, so once the wheel speed goes below 20km/hr, squeezed film effects come into play, and this is where tire chemistry/compound becomes important. So if you see the car sliding forwards during e-brake, it is because of an inferior tire compound, ABS and ESP (traction control) system. Wet traction is very complicated. Got high speed part, got low speed part and got automotive sensors/actuators. The factors influencing both can be totally opposite.
