Maybe I'm old school but to me the logical equation would be;
Braking, done approximately 65% by front wheels,
Drive, done 100% by front wheels,
Rainwater clearance (due to rear wheels following track of front wheels most of the time) probably 70% by front wheels,
Weight distribution 60% on front tyres,
Therefore surely it follows that the most grip ie. best and newest tyres should be on the front, I agree that understeer is easier to control than oversteer but front wheel drive road cars are always set up with an understeer bias and ESP will usually take care of oversteer.
If there is a logical reason why I'm wrong I'll be happy to change my view but I really can't think of one
After looking at tyre wear/stopping distance charts I think its important to realise that tyres at 2mm take approximatley 80% more stopping distance in extreme wet than new tyres.
rear wheels dont always follow the fronts, (eg going around a corner) and also the level of rain may be significant leading the water clearance being negligable, or even no clearance at all.
Also consider that aquaplaning is an issue. The rear of the car weighs less and can therefore be potentially more suspectible to aquaplaning if the correct conditions are in place, which is where the upthrust of the water over comes the displacement and weight of the tyres passing through, or over the water.
Yes ESP is a great facility, (and those that turn it off all the time are being silly, and yes i know its not 100% off..) but ESP isnt going to
help 100% of the time and driving in a manner or having a car set up that ESP is routinely required to prevent you leaving the road is simply suicidal. There is a limit to what ESP can do, aqua planing means there is little or no grip for the ESP to use and can render it near useless.
Braking; well there is a reason why more braking is done by the front than the rear (its often more than 60% front); - you can only brake as much as the tyres will allow/grip the road surface. Yes fronts brake more, - more weight and frontal inersia during braking mean that more braking force can be applied before the wheels may lock. For a wheel/tyre to lock during braking, the force or resistance applied by the brakes needs to overcome the resistance or force applied to turn the wheel via friction between tyres and road surface. This means that less force is required to lock the rear wheels, thus the brake bias applied by the car. If you further exagerate this by having tyres that behave significantly different to the fronts than the rears you are more likely to lock or loose grip.
I can understand the theory of your argument and why you may think that, but experience of many drivers will tell you new tyres at front, old at rear is a real no no.
It is intersting that you have stated in your post that tyres with 2mm tread take 80% longer to stop than new tyres in extreme wet. - ok so ask yourself this:
If i braked and my rear tyres took 80% longer to stop than the fronts did, - what has just happened?
and then think the same, but with the front more worn...
) and the Costco fitter said they always recommend to customers to have the new tyres fitted on the rear and they move the rear wheels to the front and re-balance if necessary..FOC.
