XRAY - Model racing cars

I have A T1FK05 and I am having a problem with my wheel screws, when I am running the carfor any length of time a wheels screw come out and the wheel will fly of.

This is happening towards the end of a sweeper coming off the front staight of the track. I have tried to threadlock the wheel screws with Tamiya thread lock and checking the wheel screws before every run.

Just some other details:
Track-Parking lot
Surface- Medium traction asphalt, but very hard on rubber
Size- around a medium with a straight away running the entire length

The car only loses the wheel screws in the sweeper coming off of the straight.

Two things. Make sure you use the coned washers and really tighten the screws when you mount the wheels. There is no problem loosing the wheelscrews when you need to even if you used force to tighten them down. I have run these screws for 5 years without using locktite and lost a wheel exactly once...

To all experienced Xray FK05 and T2 drivers: I have had several conversations with T2 owners and FK05 owners, who run on hot south florida asphalt, with rubber or foam tires, low-mid traction, NOvak brushless 4.5R systems or mod, and they all seem to think that the FK05 is a better car on asphalt for some reason. They keep pointing out that in Reedy Race 2006, and ROAR electric on-road, and WOrlds 2006, the T2 did perform close to the dominant level they seem to perform at on carpet, like the NOvak and Winter Nats races. Why? Can this be true? Any insight and explanation as to why the T2 hasn't really been dominating big events on asphalt? Which is supposed to be a better car for asphalt? Can anyone confirm if in fact the FK05 is a better can for asphalt than the t2 and why?