Shapeways may have some....(might cost a couple $) or you can widen them your self with plastic tubing....of course that means you have to cut them up and splice them back together....I havent done it personally but I have seen it done on here in smaller scales. I have widened tires before and that wasnt to hard as long as your cut is straight they should go back together pretty easy and if you cut them where there is a lip/step in the wheel you will be less likely to see the seam. You can always check other 1/8th scale kits also...I know the T buckets have some wider wheels...model swap meets and even asking on the forum here under parts wanted might turn up something also It has worked for me when I messed something up or it was missing.