Sitting here at discount tire getting new shoes for the wife's car and unfortunately they don't have any cooper at3 to look at, only the ATP. Sales guy says the AT3 is on back order for the size I need. Says the ATP is the newer tire. So what's the difference between the at3 and the ATP?
I'ver never tried the ATP, so all I can do is look at pics and read reviews.
It's tread pattern looks like a crossbreed of Hankook ATM and Cooper AT3, or maybe a mix between Nitto Terra Grappler and Cooper AT3.
Online, I only find ATP for sale at Discount Tire. That makes me suspect it's a Cooper AT made specifically for Discount Tire. The AT3 is sold many places. Discount tire probably makes a few extra bucks on ATP compared to AT3. That's not necessarily a bad thing, but it probably means Discount Tire has more motivation to keep ATP in stock
The reviews of ATP suggest it makes slightly more road noise than AT3 because people with ATP say it's a slight hum that's barely noticeable. My AT3 are silent (to my ears, and I have good hearing).
ATP is not available in R15 sizes. AT3 is available in R15 sizes. The ATP in R16 has less sizes and load ratings to choose from.
I think they're probably both great tires, but the AT3 is reviewed to be slightly quieter, offers more sizes and load ratings, and might cost slightly more.
I think the ATP is fine if they have it in a size, load rating, tread-depth, and price you want; but the AT3 offers more choices and is probably quieter.
Ride quality and traction are probably about the same, but that's just my guess. Reviewers like both tires.