From FAA 8400.9 NATIONAL SAFETY AND OPERATIONAL CRITERIA FOR RUNWAY SELECTION PLANS AND NOISE ABATEMENT RUNWAY USE PROGRAMS.
10. OPERATIONAL SAFETY CRITERIA FOR RUNWAY USE
d. Maximum tailwind component (including gust)
i. Dry Runway: 10 kts
ii. Wet Runway: 10 kts
iii. Contaminated Runway (< 8000 ft) < 3 kts (reported as calm)
iv. Contaminated Runway (> 8000 ft) 5 kts
Per the FM, the "maximum allowable tailwind component" is just that, maximum...