seamax deluxe 4 by 4 boat launching dolly with 14" wheels system, commercial grade quality for inflatable boat and aluminum boat max loading 600lb seamax adjustable design: these wheels have 4 adjustment positions for length and angle to adjust the leg length, push in the spring-loaded buttons on each side of the leg and either pull or push to lengthen or shorten. to adjust the leg angle, push down on the spring-loaded bar near the top of the leg assembly and move the leg assembly to the desired location. to remove the leg assembly from the bracket, pull out the quick release pin located at the top of the leg assembly.</p>our new tires are now 12” in diameter and about 4” wide. they are made of 4 ply reinforced vehicle grade natural rubber which holds up well against uv rays, heat and salt water for up to ten years</p> installation: this dolly set should only be installed by an adult with some experience in working with tools. to install the wheelset properly, you will need to drill 5/16” holes in the plywood transom for the mounting brackets. it is very important to locate the position of the holes correctly. please check carefully including checking the wheel arm position before starting to drill any holes.</p> maintenance: wash it after using it from saltwater or sandy beach. check tire pressure before every using. don’t store the wheels under the sun or beside the heat to maximize its lifetime. take the wheel arm off from the transom bracket when storing your boat. lube the spring load dolly system if needed. always keep the lock pin on the dolly bracket.</p> tire inflation: dolly tires may not be fully inflated when shipping; please only give 15-20 psi pressure at room temperature before using. best to use a car tire digital air pump to prevent tire over-inflation. tire over-inflated will cause damage and the warranty is not covered.</p> 14" dual wheel upgrade kit is available for this deluxe boat launching wheelset for heavy loading application or sandy beach use. we suggest the boat 14ft and up to use this upgrade kit, then you can have a wide enough transom to support 4 wheels operation.</p>