Ian's Grandfather is a knowledgeable guy.
I'm assuming your PT wood is at least 6 months old, if it isn't I'd wait until spring.
Clear is easiest, just spray it on and your done, but it won't last more then a year, year and a half.
Semi solids will last 3-4 years if prepared properly.
Your tires will never get hot enough to damage the seal
Personally, I have a metal deck.