1925 jd tires

[cscott]

was hoping someone might know the correct tire size for a 1925 jd ...thanks chris

[Sargehere]

I believe they are 3.85 x 27 clinchers that were used on the J models, from the time they got the "streamlined" look, the lowered frame, in 1925. I know that is the size on my friend's bone-stock 27JD, and that Coker makes them.
If you have to go to drop-center rims, or if someone already has put 19 inch drop-center rims on your JD back, during the period that clincher tires were unobtainable, a 4.00X19 looks good on them. A Dunlop K-70 even has a "period" tread-look.

[cscott]

right now it has clincher 18x3.75...they look too small and i have had points deducted for them......just bought the correct front rim and hub..still looking for rear..(this is an unrestored original )....was the 18" clincher an option? thanks for your imput

[Sargehere]

Clincher tires were stock on all J models. Clinchers were not measured by the rim size, but by the O.D. of the tire, and that's what it says on the tire wall, "3.85 x 27" is what you want to see.
Drop-center rims were not stock on most Harleys until the VL/RL era, circa 1930. I think 3.85 x 27 means a 19 inch rim. 27 - (2 x 3.85) = 19. ("A" and "B" singles were an exception, using clincher tires well into the 1930s)
I know that "2.50 x 24" clincher tires will "stretch over," and were used in a pinch, in the old days, when 3.85 x27 tires weren't available. But they look ridiculously skinny on a JD. But five inches from 24 also equals 19 inches.

[Sargehere]

Mebbe I'm losin' it. Coker makes an assortment of 28 x 3s, like this one:
http://store.cokertire.com/popular-t...all-black.html
And this 28 x3.50 one:
http://store.cokertire.com/350-20-si...wall-tire.html
So if Coker ever offered the 3.85x27 tire, they don't any more.

And page 57 of Jerry Hatfield's Inside Harley-Davidson states "The wider 1925 frame allowed wider 27x3 1/2in. tires in place of the former 28x3in. tires... based on the outside diameter of the tires; wheel sizes from rim to tim were 22 in. through 1924, and 20 in. from 1925."