TT recall, why, and poss. solutions!
10-20-1999, 08:01 AM
#12
Guest
Posts: n/a
Tire sizes
The TT comes w. 225/45/17 on 17x7.5" rims, Rolling diameter is 24.98".
I know the 235/40/17 fits, RD is 24.40"
I also think the 245/40/17 w. RD of 24.72" should fit.
I'd recommend wider rims, and of course offset also determines if they'd fit. We might even find out that the 255/40/17 w. a RD of 25.04 might fit, on non lowered TT's?? I'm not sure on this one though.
I know the 235/40/17 fits, RD is 24.40"
I also think the 245/40/17 w. RD of 24.72" should fit.
I'd recommend wider rims, and of course offset also determines if they'd fit. We might even find out that the 255/40/17 w. a RD of 25.04 might fit, on non lowered TT's?? I'm not sure on this one though.
10-20-1999, 08:49 AM
#20
Guest
Posts: n/a
Modern brakes and front/rear bias ...
The reason there is a brake bias toward the front wheels is to account for the greater effective weight bearing down over the front wheels during breaking. This means that the front wheels have more traction and can thus can sustain more braking power before braking free. The rear wheels, feeling LESS weight than under normal cruise due to the braking weight transfer, are under danger of losing traction before the front brakes and locking up. So, braking force on the rear is reduced. Usually the biasing is conservation, to make extra sure that the rear brakes don't lock. Thus the typical 80/20 split.
Whenever you hear wheel lockup, though, you probably think ABS brakes. Why wouldn't this prevent rear wheel lockup, you ask. Well, it would, and thus many modern cars are starting to eliminate the mechanical proportioning valve that creates the front/rear brake bias. Instead, all brakes receive full power and the ABS system simply keeps the braking power on the rear low enough to prevent lock up. Not only is this arrangement simpler, but it avoids nonoptimal rear braking power due to being too conservative on the biasing settings.
I say all this because I'd think that the Audi TT would already be using electronic brake biasing and thus already receiving optimal braking force distribution under all conditions. Is this not so?
Whenever you hear wheel lockup, though, you probably think ABS brakes. Why wouldn't this prevent rear wheel lockup, you ask. Well, it would, and thus many modern cars are starting to eliminate the mechanical proportioning valve that creates the front/rear brake bias. Instead, all brakes receive full power and the ABS system simply keeps the braking power on the rear low enough to prevent lock up. Not only is this arrangement simpler, but it avoids nonoptimal rear braking power due to being too conservative on the biasing settings.
I say all this because I'd think that the Audi TT would already be using electronic brake biasing and thus already receiving optimal braking force distribution under all conditions. Is this not so?