The only thing I had a problem with that seems close was my fender wells were rubbing up on my tires making some grinding noise. Probably not the same issue here.
Do you have an aftermarket front installed on your car? If so is it properly mounted? You described where you feel the vibrations but do they happen on turns only? What about high/low speeds only? What needed replacing on your 20K checkup that you didn't tend to? What needs replacing on your 25K?
Some of these questions might help you answer what's going on. If vibrations are happening on turns only, check fender wells for any debris or friction marks on tires. If vibrations are happening on high speeds, check tire balancing (again) & bearings. Worst case, take it to a mechanic or a dealership for a mechanic's educated guess (did I just use mechanic & educated in the same sentence?).
good luck on your troubleshooting