X-wind limits will be the airlines' SOP's and may not coincide with the manufacturer's recommended limits, nor other airline's limits. The reason for diverting remains with the Captain, as always! The first 747 I flew had T/O limit (dry) of 40 kts and 35 kts landing (also dry). The last 747 I flew had a limit of 30 kts T/O and Ldg (dry). These were not Boeing's limits. Wet or slippery conditions would further lower the limits.