im going to say it is not because i am reading all the specs about it on tower and it doesnt say anything about it being waterproof.
i am sure that would be one of the first things mentioned.
They do appear to be waterproof. I don't know if I would submerge it for any length of time, but if you look closely you can see that it does have a small rubber seal around the edge of the bottom case. It also has a similar seal around the heatsink.
Bigger tires are like geared up. Since the tire circumference is bigger the car will travel further from the same number of wheel rpm. Gearing up is better though, because big heavy wheels take more power to turn.
The ESC are Waterproof now.. I stuffed them full of Dielectric Grease.
Yes those wheels are little heaver but not much.
last night I ran 56(Jator Gear) 22t Pinion. and it did 64mph Verified .. was in my buddy F-150 and I drove the emaxx down a long road. The wheel about blew off the rims I could on get it to 64mph for like 1-3 seconds very hard to control!