Well, your experience demonstrates that not all LBSes are equal, nor are some of the "clerks" whom you encounter going to be equal to others ...
And, supporting an LBS may be both fruitless & thankless ...
Yet, others may be worth supporting.
FYI. I thought that BONTRAGER labeled 27x1.125 tires might still be available, but probably not ... but, if they are, check with your local TREK dealer to see if they have any in stock OR if they can order a set for you.
Regardless, I would think that CONTINENTAL, MICHELIN & SCHWALBE possibly still make 27" tires ... so, it's really a question of finding a source ... that is, contact the North American representative OR distributor.
NASHBAR (
and/or its PERFORMANCE subsidiary) may still carry 27" tires -- if they do, choose a recognizable brand.
REI may carry 27" tires.
If you contact HARRIS CYCLERY then they can probably tell you what brands are still readily available.
However, if you are not a purist, then for convenience it may be beneficial to change the wheels to 700c ...
- either relace your current wheels with 700c rims (you may be able to use the same spokes if you lace 36x4 instead of 36x3) ...
- or, buy a 'new', 700c wheelset & respace your frame's triangle, as necessary
- or, possibly, if you want to continue to use Freewheels, then you can buy a Single Speed wheelset & add a 6mm spacer PLUS redish the wheel, accordingly
BTW. My recollection is that 1985 was close to (
actually, just past?!?) the "cusp" between when 700c & 27" tires were equally common on new-at-the-time bikes, so there is a chance that if you switch to the slightly smaller 700c wheel size (
i.e., there is a 4mm difference in the radius, hence you will need a brake which has a 4mm longer reach) then you may-or-may-not need brake calipers which have a longer reach than the ones which are currently on your bike ...
- but, if you do then you can find the appropriate length, TEKTRO calipers on eBay.