Do you balance slick tires on the Challenge car?
Yes you balance all tires including slicks. I race in IMSA and PWC and all tires/wheels are balanced before racing on them. If you throw off a wheel balance weight you know it as the car will shake. As a side note (separate from balancing the wheels) to show how different each tire is, the tires vary from tire to tire so much they give us the spring rate for each tire--the manufacturing process ends up producing tires with different thicknesses/side wall strength from tire to tire and the spring rate varies which ends up affecting how our suspension responds. We match up spring rates so that a set of 4 matches what we are looking for. There is a surprisingly big difference between tires and it affects our suspension/car handling. Likewise the wheels themselves are not perfectly balanced. (weight) Balancing is important.
Pirelli and Continental give you a spring rate of each tire by report or you get the spring rates of the generic tire size from each maker and set-up your cars accordingly?
Spring rate for each individual tire (each tire is tested for its exact spring rate). We specify what range spring rates were are looking for and they give us ones that match (within a range). The exact same tire brand and size can have some tires at 800 and others at 1300 and we will match 4 that are all around 800-1000 for example (instead of one that is 750, and others that are over 1100, 1200 etc).. We have rejected a set of tires for being too far off from each other and they will give us ones that are closer to each other. To be fair this is not necessary unless you are racing and it is very competitive. For example at IMSA Laguna the top 14 cars best lap in GS were all with in 1 second of each other, every tenth was a couple spots in qualifying:
Top 3 with-in hundredths of each other, top 16 cars with in 1 second! Image Unavailable, Please Login
