Is it the same Tilt 500 you mentioned in the first post. If so if you are changing the wheels then are you planning to change the rear wheel from a freewheel hub to a freehub? Seems a good upgrade, not only will it give you likely stronger wheels and hub but the gears will be more accurate and easy to adjust and you'll have more flexibility with regard gears depending on the 7 speed cassette you fit. Taylors wheels of Germany do good quality 20" double wall wheels included a rear freehub wheel for reasonable money.