65 C10 tire scrubbing HELP???

[zach_carver]

Ok guys need some advice I have bought a c10 that had springs heated to lower has P255/70R15 tires. Now problem is my left rear tire is scrubbing the front part of the bed. The right side of the truck has LOTS of clearance. I've removed all wood from the bed due to someone half way installing it all and they also used plywood in it. So all that is removed so I could see if bed was installed incorrectly. I'm not one to half way do anything and this is driving me crazy it only scrubs with the truck is unlevel or going thru a sharp curve like. Any help would be much appreciated. We've had multiple c10s dad says he's had a few 64-66 that the gap was always a little different but never this bad.