Howdy. I'm not sure what to make of these tires. I have an old Accord that I put new Altimax RT43 on when the car was at about 30k miles. Now at almost 70k on the odo, the tread is still really good but the cracking that I see is concerning. Should I be? The date code looks to be 5117 so they're just over 5 years old. All 4 tires have the same kind of cracking on the sidewall. Are these things junk at this point or is this cosmetic? Thanks!