FWD or AWD >> DIFFERENT TIRE SIZES
 

I just had my new 245 45 16 Hankook Ventus K102's put on the front of my SVX. The old 225 50 16 Yokohama's are still on the rear, waiting for the delivery of the other 2 Hankooks! The installer said not good to have AWD with different size tires...front to back....so I put fuse in to make temporarily FWD (front wheel drive).

The Hankooks are just slightly larger.....but rears are also worn out...no tread....so, even smaller diameter...

Should I leave in FWD mode or return to normal AWD???? Which is better for this situation (I heard before that it's not good to drive too far in FWD!?)

PLEASE GIVE YOUR OPINION.....THANKS! :confused: :D

Jim, nice choise of tires, leave the fuse in till your back tires show up, and drive like a gentleman till then. If the tires were new, you could use Larry III's spedo error program in his locker, (thanks Larry:) ). When new the 225/50/16s are a little taller than the 245/45/16s. Tom

Yeah, definitely leave the fuse in or else run the risk of doing permanent damage to your transfer clutch.

One interesting thing to note, even with the fwd fuse in place, some power is still sent to the rear wheels. When Tom (svxfiles) completed the rear diff install during my 4.11 swap, we forgot to remove the fwd fuse and started her up on the lift to see if my awd was working. All four wheels spun.

I'm almost wondering if the fwd fuse just keeps the TCU locked in the normal torque split of 90/10???

-Chike

You have to remember how the transfer clutch works. The driven plates are always being driven by the transmission. Then there are drive plates sandwiched in between the driven plates attached to the propshaft to the rear wheels. Hydraulic pressure squeezes that sandwich together to send torque to the rear.

I think it's entirely believable that, with those twelve plates sandwiched together, the rear is going to coast a little just from having the driven plates spinning between them.

The transfer clutch is designed to slip pretty much constantly. The one in my wife's car was good even after 140k miles of constant slipping, which it encounters during normal operation. That's pretty awesome in my book. But you can still make it slip when it's not supposed to in ways it's not supposed to. Having mismatched (or underinflated) tires is one way. Putting the FWD fuse in and spinning the front tires is another.

Putting the fuse in because you're waiting a couple days for matching tires is fine. Just be careful and drive conservatively. No spinning the front tires. It's a better alternative than leaving the fuse out and having the car expect matching tire diameters and applying the wrong pressure to the clutch all the time.