On 27/03/2014 12:09, Bob Kuykendall wrote:
I just did a bit of web searching, and I now believe that "ET27"
refers to an offset of 27mm or 1-1/16". Given the width of 4.5", I
think that for most steel wheels that would correspond to a
backspacing of 3.81".

If that is so, now all you need is the bolt circle. The best bet is
to measure it as I wrote earlier. Although, if it is a European
glider trailer, I would put my money on 4-on-108mm.

Thanks again, Bob K.

I wrecked a Cobra wheel recently from a two-seater trailer (15" wheel, 5
bolts) and I found measuring the PCD wasn't simple or easy. There are a
number of very-close-to-what-I-think possibilities and only the
templates that some trailer dealers seem to have make accurate decisions.

The other difficulty is that trailer wheels are rarely the same as car
wheels these days. The near-universal use of bulky disc brakes on cars
and drums on trailers means that the offset on car wheels is usually
larger than that on trailer wheels. Visiting your local wrecker can be
time-consuming and frustrating. So close but no cigar!

My offset was 30 and I'll be surprised if the OP can find a car wheel to
match his offset of 27.

GC