You mean make them out of metal or something. If so there are some places on the net that you can buy them, I've made a few sets of rims on my metal lathe, but let me tell you something, the metal rims are WAY HIGH dollar. Your better off just finding some 2.8 rims on the net.

Like these are 2.8 rims and tires.
[link=http://allaboutfunhobbies.com/store/catalog/index.php/cPath/4_84]http://allaboutfunhobbies.com/store/catalog/index.php/cPath/4_84[/link]

[link=http://allaboutfunhobbies.com/store/catalog/index.php/cPath/4_79]http://allaboutfunhobbies.com/store/catalog/index.php/cPath/4_79[/link]