As you may already know, I'm a big fan of the Greenlight 1979 Corvette, and made a simple wheel swap on one a little time ago. Since that project didn't come out the way it was supposed to, I'm rebuilding it for a downhill racing championship and need some help :p

It's basically a wheel problem, I don't know which ones to choose... the original ones were D25W4 both on the front and rear, so I decided to change them to D20W4 on the front and D30W4 on the rear. I used a set of Co-Mo5s on those specifics measurements, but the rear wheels were too big and the fenders got in their way all the time. Grinding down the fenders is against the rules of the championship, so I decided to change the rear wheels to D25W5, but they don't make Co-Mo5s that size. Is there an easy way to make custom wheels or to customize existing wheels? what other diecast company makes D25W5 sized wheels besides Greenlight and Matchbox?

Also I have a couple more questions:
I plan on using plastic to build a new suspension, since epoxy slows the car down. Is there a more suited material for that?

Is there anything faster than a FTE axl? I chopped two FTE axels down to replace the original copper colored OH5SPs, but I can't decide on the new wheels...

Where should I add weight to keep the car balanced? it's a pretty long, 2 lane track we're gonna race on, should I put it all on the front axl or in the middle of the car?

So far I've finished the Chassis and the Bodywork. I still have to finish the Axels and the suspension to reassemble it

Thanks
Peter