Using a 50-nm-width ultraclean GaAs=AlGaAs quantum well, we have studied the Landau level filling factor v=5/2 fractional quantum Hall effect in a perpendicular magnetic field B 1:7 Tand determined its dependence on tilted magnetic fields. Contrary to all previous results, the 5=2 resistance minimum and the Hall plateau are found to strengthen continuously under an increasing tilt angle 0< <25 (corresponding to an in-plane magnetic field 0<Bk < 0:8 T). In the same range of , the activation gaps of both the 7=3 and the 8=3 states are found to increase with tilt. The 5=2 state transforms into a compressible Fermi liquid upon tilt angle >60 , and the composite fermion series [2 þ p=ð2p 1Þ, p ¼ 1; 2] can be identified. Based on our results, we discuss the relevance of a Skyrmion spin texture at v= 5/2 associated with small Zeeman energy in wide quantum wells, as proposed by Wo´js et al