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Double standard about fat tires Posted by Joe [Email]  (#444) [Profile/Gallery]
(more from Joe) on Mon, 19 May 2003 04:43:48
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I have a 1991 9000T 5spd. It has 151K and atleast 40K of that was used for burning up the rural country roads of Pa. I have read this 9000 board for many years and many seem to have the opinion that tire size has to match front to back and that offset must be 25-27mm or the world will come to an end. The thing that puzzles me is that I also have a couple of Porsches (295x35x18 rear and 225x40x18 front) and read the Porsche boards. ANYTHING goes on a Porsche on that board. "Stuff the wheelwells and you will feel G forces to be enjoyed only by the Gods." I have received my engineering degree from PSU and have since changed my 9000 over to fattys with no looking back. The car has never handled better.
Hear are the arguments:
1)Different tires front to back is dangerous.
-Partually correct. The big thing to worry about is cornering and having your rear wheels lockup while your front are still turn. If traction is reduced in the back, the car will rotate (uncontrolably) and you will hit a car head on or endup in the woods. Even the very best drivers can often not control this situation. Because static fiction is less than kenetic friction, the rear end wants to pass up the front. This is why all cars have the rear brakes significantly under powered and ofcourse the invention of ABS. Ratio is approx. 70% front30% rear. Adding wider rear tire does not reduce traction; Increased contact patch increases traction. The car is safer. All 200mph cars have much larger rear tires than front. It is not only because of rear drive. I run 225x35x18 8"rims rear (16mm spacers to correct offset) and a 215x40x18 7.5" rims front(8mm spacers to correct offset.) The 9000 standard 205x55x16 does not compare in cornering or braking. Not a safer car in the snow, 'though.
2)Incorrect offset causes torque steer.
-I agree. Even a 8mm incorrect offset will make the car feel aweful.
3)Incorrect offset causes bearings to wear out quickly.
-Partially correct. Too much off of factory will obviously create a torque on the bearing. However, the wider the tire the less easily it torques over under cornering loads. This is why skinny wheels fall over when you take them off the car and wide tires stand up with no problem. A euro standard is that +or-15mm is max. But again, incorrect offset in the front can cause torque steer and an unstable feel.
Old dogs go ahead and start the attack...
posted by 208.168.9...
, Mon, 19 May 2003 04:43:48 <-- Viewing This Message, Mon, 19 May 2003 13:38:47, Mon, 19 May 2003 08:24:23, Mon, 19 May 2003 08:36:46, Mon, 19 May 2003 08:16:28
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