Wheel tail isn't painful at all. It's just the muscles re-aligning themselves because of the running. Spinal issues are caused by too small wheels - wheelie tail is caused by running.
However, if you just mean that her tail is curling up when she runs, I believe all rats run that way on a wheel regardless of how big it is (at least, that's what I've been told).
If you mean she's getting wheelie tail, it will depend on how you personally feel about it. Medically, she won't be in pain and nothing will be wrong... however, some people feel as if it is painful and your personal beliefs will dictate whether you continue to provide her with a wheel or not. However, if you stop giving her a wheel... the wheelie tail will probably go away. Since she's not using those muscles, they'll deteriorate again.
I could be wrong, though! This is just what I've read about it.
Wheelie tail won't pose any danger to her safety or her health. Everyone I've spoken to with a rat with wheel tail states that the tail is still able to be used for balance and to grip things with... and of course, it can still be used to regulate heat since it's not like it's missing or paralzed anything
She'll be safe and, in reality, it's almost like a mark of health! Running in wheels has been shown in studies to increase immune response and some say even brain function.
she has a saucer and the large wheel and preffers the wheel but if i removr it she freakin dose laps in the cage rather than use the saucer ive seen her on it maby three or four times but thats it she loves the wheel though