There is a new glitch in GTA IV I may have found and wanted volunteers to try it out before I post it in the "Secrets and Easter Eggs in GTA IV" page, just to be sure the glitch is legit.
It happened when cruising around with a Turismo in Northwood, Algonquin; heading northbound on the walkway beside the Humboldt River. When i came to the spot in the walkway under the Northwood Heights Bridge, theres a pile of tires to the left and a lone tire laying in the center of the walkway. At the time, i was going at about a fair amount of speed when i ran over the lone tire.
It launched the Turismo upwards at a 90 degree angle (the rear of the car in the air); making the car tumble and flip several times before coming to a battered stop. I tried it again a few times and the lone tire did the same, as the first go. Just for fun, i found an NRG 900 and tried the same thing; it launched the NRG upside down, landing the bike on top of niko.
The posted image shows the location of where the lone tire is; feel free to try it and post your results.