Yukon Gear & Axle New Gear Break-In All new gear sets require a break-in period to prevent overheating damage. Any overloading or overheating will break down the gear oil, which will cause the ring and pinion to fail. This can be determined by inspection and will void the gears warranty. Please follow these guidelines to insure proper break-in. I Avoid heavy acceleration during the break-in process. I Drive the vehicle lightly for the first 15 to 20 miles and stop. Let the differential cool before proceeding. I Avoid heavy acceleration for the first 100 miles. I Drive the vehicle at least 500 miles before towing to retain the gears warranty. I When towing for the first time, drive for a very short distances (less than 15 miles) with the full load and stop. Let the differential cool for about 20 minutes before proceeding. Repeat this procedure two more times (45 miles total) to fully break in the gears. I Change the all after the first 500 miles. This will remove any metal particles and phosphoric coating shed by the gear set during the gears' break-in period. These towing instructions may seem unnecessary to most people, but we have seen many differentials damaged from being loaded before the gear set was fully broken-in. OVERLOADED 0R OVERHEA'I'ED GEAR OIL Wlll BREAK DOWN AND DESTROY THE RING AND PINION. Yukon Maximum Recommended Tire Size Axle Style Maximum Tire Diameter Chrysler 8.25 33 inches Dana 30 > 32 inches Dana M35 33 inches Dana M20 35 inches Dana 44 7 34 inches Ford 8.8 35 inches GM 8.5 35 inches Toyota 8 34'inches