Danny,

You should be fine sticking with the same tire you have if that's worked. If you change, just make sure the overall diameter is about the same (that figure is available for most tires). I'm actually running slightly larger diameter tires intentionally to get more ground clearance at the rear of the trailer.

I'm still shopping for replacement wheels for my older Cobra. It's a 13 x 4 1/2 wheel with a 29 mm positive offset. The bolt circle is 4 holes on 100 mm and the centerbore is 57 mm. Mine are stamped K13S133 and FAD | 4 1/2 JX13H2, which seems to indicate this was a common wheel years ago (the original Komet trailers had wheels that fit the old Open Kadett imported from Germany).

I believe later Cobras went to a 14" wheel, which seems easier to find. I'd be fine with moving up; I'd just use a lower profile tire with about the same diameter as what I have now.

What's proven difficult is that the published wheel specs don't always include values for all of the above measurements. A wider rim would be OK (there's enough clearance between the tire and sidewall now) but as you found out, a significant change in the offset would not. Nor would different bolt circles or centerbores, although there are adaptors out there to shrink a larger centerbore to a smaller size.

I'd rather stay with a cheaper steel wheel since I have to buy three of them and since I've damaged two already in blowouts (the second one running a TPMS that didn't warn me properly--when the tire blew catastrophically and the sending unit got knocked off by flapping tread, the readout continued to provide the PSI/temp that was last reported.)

I suppose one solution is to go with a zero offset wheel if that's common and just get wider fenders. I intend to replace mine anyway.

Chip Bearden
JB