Motorcycle tires wearing abnormally fast?

I've got a 1980 Suzuki gs750e cafe racer. I threw a set of IRCs on it when I first started riding it just because I had them laying around. I knew these were a cheap tire and didn't expect much. Within about 650 miles, the back tire was completely toast, I'm not talking down to the wear bar, it was a... show more I've got a 1980 Suzuki gs750e cafe racer. I threw a set of IRCs on it when I first started riding it just because I had them laying around. I knew these were a cheap tire and didn't expect much. Within about 650 miles, the back tire was completely toast, I'm not talking down to the wear bar, it was a slick. (I ride fairly aggressively on backroads, but never do burnouts or anything like that) but the tire was just squared off. (I run 28 psi in the front 32 in the rear) got a replacement (cant remember the brand) and the exact same thing happened. I almost exclusively ride on twisty back roads but it looked like I'd just sat there and roasted the back tire off in a burnout. So finally I asked a local cafe builder what tires he runs in his bikes. So I got a set front and rear of the bridgestone spitfires. I'm about 350 miles in and the rear is just about to hit the wear bar. I have friends with sportbikes that only carve canyons getting thousands out of their tires. Haven't even put 2k miles on the bike and I'm just about thru my 3rd rear. So my question is. Could this just be a result of riding it hard? Or is there something that I'm just doing wrong?
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