Will; My diesel fuel tank was directly behind the steer axle, was 15,160. Fuel full, 14,800-14,900 on the steer .
I don't know the weight difference between a 3 and 4 slide that year/ model. I did run 315's all around. Nitrogen in all tires and used a Power Tank for inflation. Sooo handy. Loved it.
78K + and no issues.