From reading this thread in the past, I determined that the new tires are not made the same... some specific chemical in the rubber recipe was banned, or something along those lines. I think this holds true for many, if not all of the Asian RC tire manufacturers. Retrace this thread, the posts are back there somewhere... or Tony might chime in & confirm.

I just opened a new old stock pair of standard m-chassis radials(55d for the M-01 - not 60d) with the old packaging, and a brand new recently-stocked pair of the same part number, and they are completely different. The old pair from the mid-90s is very soft with a white residue on them, & the brand new pair(same exact part number, but with a new hang tag label) is stiff, slick & they even have a much stronger smell. The new tires feel like vinyl