I thought I would give a little update on the Power Wheel traction problem. I have attached a picture of the modifications I made to my son's Power Wheels.
I bought a set of self adhesive felt pads used on the bottom of furniture legs to prevent floor scratches. I stuck them on the rear tires and that seemed to help a lot. I thought they would peel off right away, but none have yet.
I also ordered a set of 'Traction Multipliers' off of eBay for $15 including shipping. They are just pieces of a large inner tube cut to slide over the tires. I couldn't buy correct size tube for $15 so I just bought the pre-cut bands off of ebay. These seemed to help also, especially on gravel. They also made it a lot quieter on gravel and concrete.
I also added a wood block to the foot pedal to make it easier for my son to reach the pedal. BTW, New Holland grey is a pretty close match to the grey on the floor board.
It still spins out occationally, but it is a huge improvement over what it was without modifications. Well worth the $18 spent on modifications.