Bridgestone Re11 tire problem
 

Got these tires with rims from getyourwheels on June 2013, had 13000 miles on them, only street driving.

Notice these small cracks on the side wall and between tread, is it normal? I checked other cars with even older tires, they don't have this kind of cracking.

I'm no tyre expert, but I don't think it's normal. You shouldn't have any cracks in the tyres. It's possible that the tyre was overinflated or dried out

Max Summer tire will be subject to cracking premature; if exposed to very cold or freezing temperatures.

But my front tires are all fine, maybe because rear tires have higher heat circles?

Looking at the pictures closer; they really looked aged-either from heat cycling or left outside dormant...I didn't really want to say neglected.

both pics are for rear tires. anyway, will change them after another 2500 miles. Two new rear tires are sitting in the room.

:iagree:
You need to drive the Z more. :driving: That's age cracking from Ozone, and sun.

I'm with the other folks that think it's age (possibly neglect or abuse). IIRC, all tires made since the turn of the century have a 4-digit date code (WWYY) molded into the tire.

My rears re-11's have heat cycled out and look nothing like that. They are just hard and a little slick. They are fine for DD, highway cruising and burning rubber but not much else. I don't do any spirited driving such as canyon runs on them because they can't be trusted. I would replace those bad boys ASAP!

It's dry rot, UV and Ozone breaks down tire rubber components.
What Are the Causes of Tire Dry Rot? | Sciencing

Z is my daily drive, commute to work is only 3.5 miles :driving:

Going to move to NH in 2 months, probably the new RE-11 I am putting on will suffer more.

What do you use to clean your tires with?

just water

Why wait 2,500 miles? makes no sense. You're risky being another one of those people who don't change tires when they need to be replaced and end up wrecking your Z because a tire blew out. Just change them now.