I was for a long time a service manager for a shop that dealt with alot of imports, and I can promise you it isn't the tires. If a tire is out of balance it will shake weather you are on the throttle or not, it has to be in one or both of your cv shafts like dino said. What has most likely happened is the cv boots don't have any way of greeasing them unless you put a small pin hole in them, but you don't want to do that or the high spinning velocity wil spray the grease everywhere. The only downside you have now is to figure out which one it is. Try turning at a slow speed from right to left(preferably in a parking lot) and listen for a clcking noise. If you hear it from either side, that is your bad cv shaft. If not, the only other way to find out is unfortunatly to remve the shaft and then the boot and replace whichever joint has play in it. With the time this takes, you might want to just replace the shafts anyways, as this will save you headache in the long run. Hit me back if you have any questions.

'95 talon TSi AWD,toyo fz4 tires and 17" ASA wheels