6mm Wheel nut

[Sneeck]

Nope. Got some local locknutz and they fit perect.

Locknuts go on with more force, specially new one's since the plastic ring is new. This is what you might refer to as "apply much force" to get it on. If that's the case then there is no problem. Just don't re-use locknut's all the time, the more you take them on and off the more the plastic ring will wear and the less it will lock.