Hope this isn't a dumb question...
4wd in the rain? haha... That's funny. Does that mean that us 2wd guys shouldn't be driving when it rains outside? And 20" wheels give much better traction than the stock 17's do in rain and snow.. Bigger footprint, gets better traction.
For the record, 4wd does not change the hydroplaning characteristics of a vehicle. (Tires do, though!!) The only thing it does is make the vehicle accellerate better from a stop (on wet streets, let's not get into the whole off-roading aspects). It doesn't allow you to stop any better than when you're in 2wd. It doesn't suddenly allow you to traverse 3inch deep water at 50mph any better than when you're in 2wd. A 2wd S-10 with good tires on a wet street will outperform the baddest 4wd you ever saw with bald tires any day. And another thing... if you're driving 50mph, you can't possibly need the additional traction of 4wd. If you do, then you're driving too fast for conditions anyhow and you're not going to pay any attention to this. And as a rule on any vehicle that is 4wd (no matter what kind of 4wd, part time, full time 4lo, 4hi, shift on the fly, doesn't matter), if you drive in 4-anything on any surface other than snow or dirt, you will wear the axles and joints faster. It may be an acceptable amount of faster wear to some, but it WILL wear faster.




