I would like to know what are the mesures of the tires and whells that i can put on my G 300D for more speed on the highway (120 - 130 Km/h are enough)

Contact Tirerack for specifics on size fittments. If you are trying to change the overall rolling radius be advised that speedometer and odometer accuracy will be off. Tirerack has an ultra complete database that covers just about every modern or semi-modern benz. Their staff should be able to tell you exactly what size is right for your intended application. You could also try contacting Brabus regarding wheels and tires, their heavy European experience is hard to beat.

Hope this helps...Lee