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Originally Posted by drivemusicnow
quick hijack:
What exactly is the difference between a bias ply, and a radial tire. And why would alignment not matter on the bias ply?
and why would you want that much toe out? that could get scary under braking  |
Not an expert on tire design but the simplified answer is a radial tire has steel radials holding it all together while a bias ply is simply corded.
A radial tire offers the opportunity for a very stiff sidewall so the tire doesn't "roll" in a turn as much (hence the need for a more camber to keep you off the outer corner while turning). It really came into its own in the 60s as a street alternative to bias ply
Bias Ply offers the better grip of the two but doesn't last as long and is more prone to blowouts, rolling off the rim etc. They are what almost every car made prior to the mid 60s came with. The sidewall is not nearly as stiff so when it rolls its kinda like rolling a doughnut (the kind you eat). Provide you have tread on the top of the sidewall you simply roll into more grip. More of a roll then bit type of design so it takes some getting used to for those who don't remember driving their 4500lb detroit iron around with 'em on. A motorcycle tire is a decent example as it is round and has tread on the sidewalls. To my knowledge there aren't any "real" race tires, as in non-street legal slicks that aren't bias plys.
As for toe out up front. It helps greatly with turn in. Most street autoxers tend to run about a degree give or take. Only real affect is it becomes kinda twitchy on the highways. I think I remember reading the max you could get out of most subarus was about 2.5 so we'd probably settle around 2 as if one side goes to 2.5 the otherside might only go to 2.3 degrees.