Miata Mailing List: December 1997, Message #269
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From: 	"Werner Cassel" <Cassel@post.med.uni-marburg.de>

Subject: Re: Snowtire position vs. tread depth

Date: 	Wed, 3 Dec 1997 03:04:47 +0000



On  2 Dec 97 at 21:59, Bruce Labitt wrote:



> I recently picked up a set of used Nokia Hakka's for winter use.  I

> have two tires with "full" tread depth and two with "half" depth. 

> Which pair should go where and why?  FWIW, the full treads are now

> installed in the rear.  Should they be up front?

> 

> Bruce

> 94R System III

> 175/65-14's "half and half"

> Nashua NH

.......



Bruce,



IMO, they should stay on the rear. Braking will be much safer this 

way. Imagine braking on the edge of adhesion. If the front tires lock 

up and the rear tires don't, your Miata goes straight ahead (in a 

dynamic sense, it "hangs" on the rear wheels). This is the situation 

for better tires in the rear.

If the rear tires lock and the fronts don't, there is a very high 

chance to spin. Imagine a pendulum with the weight on the top - it 

will come down. The car pushes forward, no grip on the rear, the tail 

comes around.

While in virtually all cars, brake balance is set so that the front 

locks up first (for the reasons given above), this can be changed by 

less grippy tires on the rear. 



FWIW, YMMV



Werner

P.S. The better tyres rear was confirmed by driving instructors in 

last summer's driving school.

P.P.S. Went home in the snow yesterday. The Ford in front of me was 

doing maybe 10 mph downhill, and the tail was all over the place 

during braking. Zero problems for us (winter tires, better tires in 

the rear)