Threads For Alloys?

[ozzy666]

lo all just had some 17" alloys put on my 1991 celica and noticed that the nuts that go on only grab about 10mm of thread.i bought the wheels from rochford tyres off the internet and they assured me that the wheels would fit but i would of thought that there would of been more of the nut grabbing the thread.the nuts are bout an inch long and tapered and when on, i can count 6 theads when looking at them so theres probably only bout 10 threads actually been screwed on?is this enough? ?????