Rear brake pads worn out before front

[starkey188]

05 H2, truck has been steering or turning hard like when in 4 wheel drive lock on asphalt. Took tires off to rotate tires and have a look and noticed rear brake pads are worn a lot more than the front. I jacked up front end to make sure front diff wasn,t locked and it is free. when I put into 4 high lock and turn on asphalt the tires really grab so I think 4 wheel drive is fucntioning ok. Maybe the rear brakes are draging on turns somehow and and causing the hard turns. I checked e brake line for any damage and found none. I need to change rear pads today but would like to fix other problem first. Any help would be appreciated. I drive this truck mostly on dirt roads.