Tire Size Confusion

Submitted by markk900 on Sat, 03/10/2018 - 08:10

When I acquired the 38 Road Racer, it still had original Dunlop Speedster tires in red, however the original wheels had been replaced (from the history of the bike in the mid 1970s).

 

Here's the confusion:  the tires are marked 28 x 1 1/4 ("For Endrick Rim"), which should translate to 622mm (or 700C) size in more modern terms.  However, the  replacement wheels have French Chromlux 27 x 1 1/4 rims, which are 630mm diameter.

Would it have been possible to mount those tires, or am I getting the translation of 28 x 1 1/4 wrong?  I can confirm the tires were on those rims though when I got it they were deflated and rotting; but I know for certain the bike was ridden with the tires on the rims (the bike came from family).

 

On a side note I found an almost perfect match for the tread pattern in a Kenda tire, but its only made in 24" size!  Does anyone have a source for close matches?

3 Comments

Submitted by T-Mar on Sat, 03/10/2018 - 08:56.

Hmm, I thought we addressed this for you a couple of years ago, on BF?

Regardless, 622mm bead seat diameter, as used on the majority of CCM bicycles of this vintage, typically used 28" x 1-1/2" tyres. The slightly narrower 28" x 1-1/4" tyres as used on the Road Racers were 630mm bead seat diameter, more commonly known these days as 27" x 1-1/4". 

Submitted by markk900 on Sat, 03/10/2018 - 10:16.

Thanks T-Mar - I don't think it ever did get settled there, at least not this clearly.  But thank you.

Submitted by markk900 on Sat, 03/10/2018 - 10:21.

So T-mar - went back in BF and you were indeed just as clear there - I guess it just left my head!  Thanks again though.