I am having difficulties installing Schwalbe Marathon Plus tires (ETRTO 622-28 700x28C) on Jalco DRX-20 rims (16-622). If I am reading the Sheldon Browns tire sizing guide correctly, this is not a problem with tire width. I've tried this technique but the tire is too stiff to install it without levers. Last time I did it I broke two composite levers, this time I pinched two tubes. Previously I had a slightly wider rim (perhaps 18-622, but don't remember exactly) and while it was a little tricky to get them on, it was still do-able even without levers, whereas now I am thinking it's not possible. Is there any other tricks for how to get the tire on the rim? Could width be a factor in how difficult it is to fit? I'd be grateful for any advice.
Marathons are a known-pig of a tyre to fit to any rim. You're not alone.
The first fit is always hardest. After that they go a little easier.
Use three tyre levers, ideally ones with thinner blades/scoops/shovel ends.
Leave the tyre lying flat somewhere warm for a while before you start. This brings the rubber to a slightly more elastic state. Hanging up on a hook tends to slightly deform the tyre. I suggest you wash your rims while the tyres are laying out in the sunlight.
Wash your rims - it doesn't help get the tyre on, but you'll be less dirty and you'll have a better grip. Take the chance to renew your rim tape if needed - and if you do, use a thin tape not layers.
Now the hard bit. You want to get one bead into the rim all the way around. Make sure your tyre rotation is right at this time (guess how I know this...)
Then fit your tube's valve through the hole, and then lay the tube in the tyre. Leave the tube fully deflated.
Starting at the valve, get the second bead into the rim. Work around and at some point it will just stop popping over the rim's flange.
The trick now is to use velcro ties, tape, cable/zip ties, or even string. Go back to the valve, and make sure both tyre beads are sitting in the deepest valley of the rim.
Use your straps around tyre and rim (ie pass between two spokes) and cinch it down firmly to hold the bead in the valley. Work away from the valve in both directions. At least 3 ties, maybe a 6 will be needed. I like velcro ones cos they're reusable. My little 12" tyre went on with just 2 ties.
Also while doing this you want to "pull" the tyre to gather up all the slack possible and draw that extra around to your last working area.
Imagine you're trying to get into some really tight cycling bibs/tights/knicks and you get the idea.
Back to the working face, use your tyre levers to slowly work both ends of the overlap. Do be careful to avoid pinching the tube cos it would suck to do this again.
If its just not working, you can use a spray bottle with clean warm water and some dish soap to lubricate the rim area. Never use oils or grease. The dishwash liquid will wash off easily and if trapped in the bead will do no harm.
Some people find this process easier with a helper - a third and fourth hand are quite convenient too as are a second pair of eyes.
Don't worry about the future - once the tyre has been on there for a while it will be slightly easier to remove and refit.
Some people swear by the Quick Stick / Stik
And some people prefer the X tool
I've never used the former, but I own the latter and while its interesting is only slightly different to normal, quality tyre levers.
It's not to do with the width of the rim, its down to manufacturing tolerances.
Some tyre/rim combinations go better than others, however only experience and a lot of internet searching tells you bad combinations.
Marathon plus however is well known to be tricky to fit, with the common 'joke' that it's a good job they never puncture, because once on, they'll never come off again.
There's a tool for this specific job, which is less likely to pinch the tube than using a lever. A bead jack lifts the tyre onto the rim by hooking the bead. Kool Stop's version is sometimes branded tyre mate. That's what I use at home; on the road, good composite levers do the job, but then the tyre has usually stretched a little from being fitted.