Pistonart and evomaster3000 are both right. Putting larger wheel on will affect the handling and ride. Wheel weights are dependent on how they are made and therefore usually dependant on price. Cheaper wheels are usually heavy and vice versa, but not always!
I would stay away from replicas as most are made in China and are not very well made. There are some good replicas out there, but you can't tell just from looking. I would recommend a well known brand who can offer you a good warranty, also usually these will not be overly heavy as well.
If you are really into the performance side you can get bigger wheels that are lighter than the originals which will improve acceleration, braking and handling and still look good.
Un-sprung weight is usually the equivalent of 4-6 times sprung weight. On a Porsche Carrera by swapping to carbon fibre wheels you get performance gains equivalent to 44bhp!!
I hope this helps, take a look at our site and let me know if I can offer any more advice.
John.