I had a 91 Mr2, did the same thing. I had a friend that rode with me to work and he had this 90 degree ture I took at 40, we thought we would just keep going up in 5 mph inc. I can't say what speed exactly we were doing but I do know it was over 55, the ass end slid out and the next thing we know I was over the curb and parked in front of this ladies front door! any faster and we would have been watching tv with her. It tour up a wheel and both upper and lower linkage on the pass rear. 500.00! They will hold a corner!
As to his 90, not even with mods on it would it happen.