As air brake certified diesel mechanic. I believe that if your rigs does have full airbrakes you will have self adjusting slack adjuster if you just try to tighten them you can do damage which will cause them not to work correctly.Self adjusting brakes became mandatory in the late 90s on trucks im sure rv were also affected.if your not sure please have mechanic look at brakes its not worth trying to save a few dollars if your safety is at stake