A couple of questions for you.
What part of the country do you live in?
Do you want to run sprint tracks, (built specifically for karts) or road race on the big tracks?
I did sprint racing locally in a TaG kart (Touch and Go) for a couple of years until a couple of my sprint racing friends in Reno talked me into checking out road racing at Thunderhill Raceway in Northern California. I’ve been road racing ever since. Entry fees are higher, but you get more track time. Entry fees run around $250 – $300 for most road races. Sprint racing is considerably cheaper in the entrance fee department. (about $30 – $50) Not to mention unless you live somewhere like Northern California, where we have several road racing venues within a half day’s drive, road racing will require a travel budget as well.
A set of tires will last a race day, but some change them for each race. Depends on your budget. I’ve run them for 2 races before. What type of racing you do might dictate what kind of kart you buy. Road racing is best in a shifter kart, while sprint racing is better in a single speed kart. (My opinion) Also, sprint racing seems more sensitive to kart age, as the newer karts usually have the new ‘tricks’ on them to make them a .10 of a second faster, while in road racing it doesn’t matter quite as much, as it’s more of a drafting thing on the big tracks. I’ve been running an older kart (2006) and run mid pack in it. The big difference is the speed. Sprint racing, you will top out at around 65 – 70 mph at most tracks. Road racing, you’re doing in excess of 100 mph at most tracks. Although it IS fun to run a road track in your kart and find out you’re 8 seconds a lap faster in your shifter kart than in your Porsche.