I have a 83 Trek 500 with (original) 27 in. steel wheels. The tires on it now are Kenda 27 and 1 1/4.
I'd like to put smaller tires on it so it feels a little bit more like a road bike to me. From the information I gave could anyone possibly suggest smaller tires that would work?
Can I use 700c mm tires on it?
Thanks very much for any help.

You cannot put 700c tires on 27" rims. They are slightly smaller diameter.

Here is an excellent resource to help you understand tire sizes and naming conventions: Sheldon Brown's Tire Size Page

If you go to 700C wheels and tires, then for a tire of the same width, your total wheel/tire diameter will only be 16mm or about 5/8 inch less. So I'm not sure what feeling it is you think you'll get with a 700C. Possibly it's just a new bike you need. You are allowed more than one. <grin>

In the vintage day of the bike, it was pretty much a low end road bike for the casual and recreational rider. The bigger thing that might be making it feel different is that 27 x 1¼ tires are 32mm wide. Many road bikes for more fitness or competition oriented cyclist BITD of that Trek would have been on much narrower tires. The 1983 Trek 560 came with 700C tires in a 25mm width. If you put 27 x 1 1/8" tires on your Trek, you might get a little more of that feeling you seem to want. Those tires will have a width of 28mm which is the width tire many are riding on their road bikes today. More than a few though are riding 700C tires in the same width as your 27 x 1¼" tire.

If you browsed the article linked in the previous post, then you should realize you will have to get new wheels and tires for certain and maybe have to change the brakes. Probably more cost than the bike is worth not counting sentimental value.

+1 on Panaracer Pasela.

Thank you very much for all the information and answers.
I have a better understanding of this now
And I stand corrected on the wheels. They are aluminum.

Most early 80s 27" bike have enough brake reach to span the 4 mm difference to the rim of a 700C wheel. (630-622)/2 = 4

That gets you two good things. Much, much, much better tire selection, and usually the ability to go up one width. So, if you've got 27x1-1/4" (probably somewhere between 30 and 32 mm) on there now, a change to 700C would likely allow you to run 38s, or 32s with fenders.

Good-quality 6/7 speed 700C wheels are easily found at your nearest bike co-op. Wheels, tires, new brake pads, (yes, you need new brake pads, unless you've already swapped them out,) you should be able to make it happen for under a hundred bucks.

--Shannon

Thank you very much for that. I'll check it out

Be aware that the current trends are toward wider tires, not narrower. A quality casing with a wider tire will give a better ride with no sacrifice in rolling resistance. The challenge you face will be finding that quality tire in a 27 inch size. The market has stabilized on 700c (622 mm) wheel size and that is where the wide choice of tires is. If you switch to 700c wheels, you'll need to check that your brakes will reach to the smaller rim diameter.

Nope. 8mm or, in the goofy ‘Mercian system, 5/16”. 27” wheels are ETRTO 630mm. 700C are 622mm.

The rest of your post is spot on.

I knew something was wrong when I wrote that. Now I see that I was using the diameter as a radius.

Thanks for setting me straight. I even looked at that several times after I posted it because it was nagging me. But I never realized my error till your post.

Put a magnet on the rim and if it sticks it is steel, if not it is likely aluminum. Not that it makes any difference in a practical sense. Make sure you put some new brake pads on the bike if yours are old and hard. I vote for the Pasela brand tires too as I have put quite a few miles on a set of them in 27" size and they have worked great. Also the one post is right about the current trend for road bikes towards fat tires, most of the latest bikes are running 1 1/4" tires again, which is the equivalent of 32mm. So what is old has become popular again. I kept the 1 1/4" size on my 27" bike.

I don't see why narrower tires will help .... nor smaller wheels. Narrower tires on smaller wheels might be marginally lighter and spin up faster, but beyond that .....

I guess my confusion comes form the idea of "more like a road bike" .... how does a road bike feel? What characteristics are you trying to diminish or emphasize/ What sort of performance changes are you hoping to make?

To me a Trek 500 (https://thecabe.com/forum/threads/trek-500.149780/) is a vintage steel-frame road bike ... a "Classic" road bike. What could make a dedicated road bike feel "more like a road bike"?

I have a pair of 1980's bikes, a steel Raleigh and an aluminum Cannondale. I cold-set the Raleight to 130 mm so I could use a modern drive train, and I converted to 700c wheels because I needed new wheels anyway (I also swapped in different brakes to cover the extra reach.) The Cannondale, being aluminum, could not be cold-set so I compromised with a modern 3x7 and 27" wheels.

Both feel like road bikes.

I suspect the 'feeling more like a road bike' may be something of a visual perception thing rather than ride sensation.

That being said, some of those Kenda tires are definitely a heavy slog and the 1" Paselas should be faster. An additional upgrade would be TPU tubes which are really lightweight. You can use 700c tubes on the 27" wheels (RideNow brand are what I use).

As @SurferRosa points out, steel rims would not be original for that bike. By "smaller tires," do you mean narrower width tires or smaller diameter? There are 27" tires available in narrower width, if that's what you mean.

You cannot install 700C tires onto a 27" rim, but you could replace the wheels with 700C diameter wheels (or rebuild the current wheels with 700C rims, if you're up to that task). 27" rims have a 630mm bead seat diameter, while 700C rims have a 622mm bead seat diameter, so the 700C wheels would require you to be able to lower the brake pads by 4mm in order to reach the rim brake track. If your brakes cannot accomodate that, you can replace the calipers with longer reach calipers. Tektro, for example, makes an affordable long-reach, dual pivot caliper that would work nicely.

Other newbies should take note: the above is wrong.

Aluminium rims are MUCH better at braking in the wet, which is eminently practical.