Straight-Sided Rim Tire Replacement
 

I have a 23 year old Fuji touring bike that has straight-sided rims (there are no hooks at the end) and am having a difficult time finding a tire that will not separate from the rim when pumped up. My LBS sold me a Continental Sport 1000 tire and a Kendal tire both keep separating from the rim. I have done some research and think that there must be a different tire for older non-hooked style rims and then all the rest that have hooks like are sold on bikes now. Can anyone substantiate my theory and point me in the right direction to source some tires that will work? Thanks a bunch.

John

Might be something wrong with the rim. I have a lot of these old non hooked rims and don't really have any trouble with them. The Continental Sport 1000 is one of my favorite "cheap" tires for my old 27" wheels. I don't like the Kendas at all. I have to say though that I don't inflate the tire all the way up to the maximum pressure allowed for the tire. On the Continental, unless you are very heavy, try just inflating it to 75 or 80 psi and see if that works for you. The lower pressure will also give you a more comfortable ride at a negligible loss of efficiency.

If you do not have hook rims you may have to run at a reduced pressure. clincher tires have gotten better over the years and are now rated to higher pressures than in the past. Part of this is undoubtably the development of the hooked rim. I have an old bike with straight rims and use Armadillo tires. Although the tires are rated to 120 psi, I run them at 100 psi and do not have problems with either rim blow off or pinch flats.

At last reort, you could get some cheap tires at Walmart (they carry 27x1-1/4 tires). They aren't the best tires around, and are rated only to about 80 psi, but they stayed on my old rims with no complaint. I switched to Armadillos because I don't like flats.

I use 70 PSI 27 x 1-3/8" knobbies on the only two flat-sided rims I have not either scrapped or given away. When these tyres wear out, I will probably retire these rims, as well. Modern higher-pressure tyres and hook-beaded rims are much more reliable, safe, and efficient.

Thanks for the reply. For 1000's of miles, frim 1978 to the early 90's, I rode at 80 psi and never had a problem with the tire separating from the rim. I am not that heavy at 160 lbs. Last fall I started riding again so I bought a new set of tires, pumped them up to 80 psi and have had the back tire pull off the rim 4 times. Luckily it has been at low speed. This last weekend, I caught it in time and let the air out before the tube blew. I reseated the tire and pumped it up to about 60 psi and before I could get it all pumped up it separated again. One thing that I noticed is that on the Continental Sport 1000 is that I could remove the tire from the wheel with my hands with without much effort even with no tools. Back in the 80's, it was almost impossible to remove or remount the tire with no tools. It sure seems like the bead diameter of the tires now is bigger than the bead diameter was in the 80's. It could be my imagination.

As everyone has pointed out you MUST REDUCE PRESSURE. 80 P.S.I. is about max for those rims.

You tires should be considerably wider than the rim.

Are the rims spread? In other words are the side walls parrallel to each other or do the 'flair out' at the tops? If they flair out you wont have much luck. Good luck,

Jim

I'll take a look tonight when I get home. The rims might flare. I'll check with the calipers. Thanks for the help.

What size tires are you pumping to 100 psi - 27 x 1 1/4?

I've got a Weinmann Concave 700 rim on the back of my hybrid, circa 1990. Another member here pointed out (I wouldn't've thought about it otherwise) that it's a flat-wall rim, with no bead hook. I've had a coupla cheapo Kendas on it, pumped up to about 70 psi, without jumping the rim. I'm presently running a Maxxis Overdrive 700x38 on it, pumped to about 75 psi. I figure the wide width is holding it on pretty tight.

Generally, I find wild variation wrt. difficulty of mounting with various rim/tire combinations. It's probably a function of both the bead diameter of the tire and the "wall height" of the rim. For your rims, I would just recommend finding a tire that's pretty hard to mount. You may even be able to compare relative bead diameters of various tires at the LBS by hanging them next to each other.

I use Specialized All-Condition Armadillos 27x1-1/4. The tire sidewalls state recommended pressure of 115 to 125 psi 'with hook bead rim'. The first time I tried to inflate them on my straight rims, one of them came off the rim and blew the tube at about 120 psi. I tried 100 psi and have not had any problem since.

Note that these tires have very stiff sidewalls for flat protection which might make them more amenable to higher pressure on a straight rim.