Tyre position choice

Aside from the argument over which tyres should have been on which end of the car, the mistake you make was to lift off the throttle completely on an understeering FWD car. That's the easiest way to make a FWD car spin.

The message from snipped-for-privacy@italiancar.co.uk (SteveH) contains these words:

It wouldn't of mattered what tyres were where. As has already been said, you shouldn't lift of the throttle on a front wheel drive during oversteer, or while aquaplaning. You should only lift of the throttle during understeer.

So you had old worn tyres put on the front and new ones on the back - you didn't have new ones on the front. If it's a front wheel drive car you would have been better getting new tyres on the front.

Wow, that's worrying....

At what speed was the car moving at the very point of the aquaplaning? Be as accurate as you can. What is the most shallow depth of tread you can find on the two front tyres (4 month old, so full depth. Right?) At the time of the accident, was the back laden with heavy stuff (unusually, inappropriate front-rear weight distribution)? Were the front tyres at within 10% of the recommended tyre pressure?

The front tyres are ContiEcoContact which are reputed to be pretty good in dry as well as wet conditions. Are they the EcoContact 3? The "Which" magazine rated them the winner in a tyre test some years back (there were not many brands in the survey unfortunately). Maybe they have been superseded now by other xxxContacts, such as PremiunContact, TourContact, and WinterContact. The last was the winner in an all-season tyre survey in ADAC (the German AA equivalent with a circulation of ?13 or 18 million) 2 years ago. Last October, a winter tyre survey found they were only average compared with the other tyres in the test, chiefly because of their relative lack luster performance in the wet! So the picture is constantly changing! For those looking for a superior performance tyre, sadly ContiEcoContact can no longer be considered as the champion.

Peter Spikings wrote in news:newscache$onhb4j$iwh$1 @news.powernet.co.uk:

New ones should be on the back, and don't lift off on over steer.

:)

Normally when the car starts under-steering I either apply near to full lock and control how quickly I turn with the throttle or (preferably) I ease off a bit either on the throttle or the steering until I get traction back depending on whether or not the second method will work or not - the first method works better when I've unexpectedly hit some black ice and need to change direction immediately :) Neither course of action felt appropriate in this case because the loss of traction wasn't caused by not having enough grip to get round a bend at the current speed.

I think I see why it happened now though, as I came off the throttle it started engine braking so as soon as the back wheels lost grip due to aquaplaning while the front wheels had enough grip to apply that braking force it made the car swap ends ;)

Thanks,

Peter.

They insisted :) I think it's so that if you do push the car too hard you'll under-steer instead of suddenly over-steering as the back end steps out.

Peter.

Yes, noted for next time.

Peter.

When its dry, its very unlikely you'll oversteer in a front wheel drive fiesta. However when aquaplaning you want as much tread as possible on your front wheels to dispel the water and therefore still be able to steer. In these conditions soft/hard compounds will make relatively little difference when compared to tread depth.

When aquaplaning, the natural reaction is to steer too much as nothing seems to happen when you try turning a little. Unfortunately when you're through the puddle and it catches again your wheels will be well out of alignment and the snatch could spin or even roll the car. That's what happened to a mate of mine who now has permanent back problems.

AFAIK swapping the rears to the front used to be done to prevent ageing/cracked rears on low mileage cars.

I would keep the newest tires on the wheels that steer/brake.

New tyres are *always* put to the rear, giving better (relative to the front) traction at the rear wheels. The car is much less dangerous to drive when grip is lost in the front than when lost in the rear.

When grip is lost in the front wheels, directional control is lost. The car moves forward more or less in a straight line. If then the car, due to the almost inevitable unequal traction of the two rear wheels, veers to one side it will continue resulting in a circular motion or a spin. At this point, if traction is regained at the front, a brisk turn of the steering wheel in the same direction as the spin, and once the car starts running in that direction (the feel of the motion is different; a spin with no traction and a run in the same direction, i.e. with traction, feel quite different) turning the steering wheel quickly in the opposite direction will stop the spin and regain complete directional control of the car.

When grip is lost in the rear wheels, the back end can swing to either side giving the impression that the car is spinning, i.e. it can take the form of an oversteer. But this time, the pivotal point of spin is somewhere between the two front wheels. To control the direction of a moving and spinning car using the front wheels with a spinning pivot between them is extraordinarily difficult, not least because the spinning velocity as experienced by the driver, now sitting closer to the pivot, appears to him to be much faster (compared to spinning with its pivot at the rear of the car). So, loss of rear traction is much less manageable than loss of front traction.

In aquaplaning - and here is the crucial difference - if the front wheels are involved, they are *floating* on water. To emphasize, they are not on terra firma. Consequently, no directional control is possible whatsoever. There is no subsequent regaining at the front either as on dry land. To try to control a car with its front wheels in aquaplane is futile! In reality, the fate of the car is in the lap of the gods until, that is, the car comes off the aquaplane.

New tyres have release compound on them. Normally takes a week or so to wear off, and makes the tyres nice and slippy. You'd have probably have gotten away with it if the tyres hadn't been rotated.

New tyres are lethal in the wet because of the release agent used in the moulding process, they need to be run for around 100 miles before they will work as they should.Tyre rotation should also be avoided as the tyres have worn to the geometry of where they were fitted, you were basically driving a car with 4 worse than bald tyres, what you did with the throttle / steering had little to do with the loss of control.

Of course though, the direction the wheels are pointing in will be important when the aquaplane ends....

Incidentally, does the direction of the wheels have any bearing as to when the aquaplane ends? The front wheels are still turning (they're being driven) and the channels run parallel to the tyres - so would ensuring the tyres are parallel to the direction of travel aid in ending the aquaplane earlier?

The main reason for putting new tyres on the back, is so that the rear of the car has better grip, and is more likely to understeer than oversteer.

The thinking being that it is easier to correct understeer, than it is to correct oversteer, should loss of traction be encountered.

This is the advise coming from all the major tyre manufacturers.

Yes, this is the norm - every tyre place ive been to does it. Stupid, quite frankly. I drive home and re-rotate them.