Should I use the 4WD (or 2WD) to pull my ski boat up the rather steep concrete launching ramp? Background: I bought a '15 SR5 4x4 in December 2014. Now has 6k miles. I have a 5,500 lb Four Winns ski boat (194 Funship). The concrete boatlaunch is pretty steep (maybe 10 degrees)? Is it better on my 4Runner's engine and transmission to use 4WD or should I use the 2WD? BTW, I had an '07 4Runner 2WD and it pulled the boat up the ramp ok. I'm just wondering if using the 4WD would be better on the vehicle. Thank you.