People need to be careful with shore readings. It is not the only indicator for differentiating tires. I can show you 5 different tires that read 30 shore (Pink, yellow, green, aqua, and gas fronts), yet they all are quite different in performance and wear. A durometer is only good to COMPARE TIRES IN THE SAME FAMILY of rubber....such as gas fronts or gas rears to each other. It does no good to compare a pink to a yellow. They may both be 30 shore, but they are very different tires. Compare a yellow to a white, gray, or black. Pinks need to be compared to magenta, double pink, lilac, purple, etc.
I know this is a gas thread, but the topic has been rather broad so I thought I would add this.