Rim width vs tire width (now tubulars!)

[cribbit]

EDIT: Resurrected this to follow up with a question about tubulars specifically, now. Previously was asking about clinchers.

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There are various charts that say the range of rim widths to use. But then there are things like 25mm rims that claim to work well with 28mm tires. There are some sources saying that the old rim width recommendations were actually stopping too low and that you can use rims that approach 1:1.

I think the risks of too narrow a rim are obvious, but the risks of too wide a rim are harder to understand.

Does anyone have experience using overly wide rims with tires only a little wider?

EDIT: Referring purely to inside width of the rim.

[GregL]

Originally Posted by cribbit

Does anyone have experience using overly wide rims with tires only a little wider?

Not sure if they're "overly wide," but I use Kinlin XR31T rims (24mm wide) with Continental GP4000S II tires (23mm wide). The tires measure out to 25mm wide when inflated to ~95 PSI. They ride very well. No issues under my 170 lbs., including lots of racing.

Greg

[Bradford]

I use GP4000 25s on a 23mm width rim and the measure out at 27mm. Absolutely no problems at all.

The 28s, which measure 31.5 on the same rims ride better, but the 25s are great on the two bikes that can't fit the wider tires.

[PacNW2Ford]

remember that many rim/tire width charts are referring to inside width, not the often stated outside width.

[cribbit]

Originally Posted by PacNW2Ford

remember that many rim/tire width charts are referring to inside width, not the often stated outside width.

I should have been more clear, I am as well.

[dem]

DT Swiss includes a chart with internal rim width vs. tire width. I assume their recommendations are VERY conservative, but probably gives a general idea of what is reasonable:

https://dycteyr72g97f.cloudfront.net...WEB_ZZ_001.pdf

[cribbit]

Originally Posted by dem

DT Swiss includes a chart with internal rim width vs. tire width. I assume their recommendations are VERY conservative, but probably gives a general idea of what is reasonable:

https://dycteyr72g97f.cloudfront.net...WEB_ZZ_001.pdf

It's a little less conservative than others I've seen.

What can I expect to happen if a rim is too wide?

[bitpuddle]

I run 23c tires on 21mm internal rims without issues.

Hed says it is safe, but it is way out of range if you look at the ETRTO-based charts. I think those charts were made before Kevlar beads, before tubeless-ready tire shelves and when manufacturing tolerances weren’t as good.

When using tubes, this is ok now. If you are going tubeless, running pressures for the road, I’d be much more careful.

[dddd]

Originally Posted by cribbit

It's a little less conservative than others I've seen.

What can I expect to happen if a rim is too wide?

There can be increased sidewall exposure, while the tread cap itself makes a bigger patch on the road.

Wider rims can be very much heavier, but less so today.

I used to race XC using 45mm Panaracer Smoke tires on i13mm Mavic road rims, and had no problems at all other than that it was difficult to get the wheel installed past the brake pads.

I currently run 27.5" X i51mm alloy rims on my hardtail with 2.3" tires, which flattens the tread cap, so puts down more tread. One can't corner very sharply on our dry, loose (thus slippery) trail surfaces, so the flattened tread cap is appropriate here for best overall traction.

[veloduffer]

I think that for high pressure applications, like road tires, rim and tire width combinations can be more varied/flexible as the pressure keeps the tire bead hooked to the rim.

It is low pressure, high volume applications like mtb and cross where the tire/rim combinations require more consideration.



Sent from my iPad using Tapatalk

[weiwentg]

Originally Posted by cribbit

It's a little less conservative than others I've seen.

What can I expect to happen if a rim is too wide?

Well, I've had a bunch of 25 or 26mm clincher tires (i.e. with tubes) on Pacenti SL23 v1s, which are either a 19mm or a 20mm internal width. So, by the chart, I should be dead by now.

For the record: 25mm Michelin Pro Race 4s, 26mm Specialized Turbo Pros, and I just put a 25mm Continental GP 4000 s2 on the front.

[oldpotatoe]

Originally Posted by cribbit

It's a little less conservative than others I've seen.

What can I expect to happen if a rim is too wide?

It may be hard to seat the tire is all.

[marciero]

I dont think there is a safety risk either way, within reason. If the tire seats properly you are good to go. Narrow rims were used with wide tires for decades. I used Open Pro with 35 tires for years in all kinds of riding. On the other end, I have 42 tires on a 27i rim. Before inflation there is a gap between bead and rim on both sides all the way around. My intent with the rim was for 48 tires, but once inflated the bead seats properly with the 42. I run them in the 40's for pressure but typically overinflate to get it to snap into place all the way around. Again if you get it to seat properly you are probably good. As veloduffer suggests, low pressure high volume need special care to seat. I would add supple casing to that mix of special care factors. Caveat might be for hookless rims but maybe not.

I found this while looking for Open Pro inner width
https://www.slowtwitch.com/Tech/Impl...idth_2803.html

It's a bit dated, and a little overly conservative IMO, not recommending "anything less than a 23mm tire on a rim that is ETRTO 17c (or 23mm outside-to-outside)", though acknowledging that "many people are using this combination today without issue."
Indeed, isnt 21i (think Belgium plus) with 25 tires pretty standard? I would guess that more than a few paceliners have used Belgium plus with 23 tires.

[OldCrank]

<<< Belgium plus with 23 tires >>>
This.

I put tubeless 23 Schwalbe Ones on Ardennes Plus.
Not only did they seat just fine using an old floor pump without sealant (added that later)
but they turned into 25s!!

What sort of Black Magic be this??
hoohoooo

They've been rolling just fine for a few months.

[saab2000]

For pure road riding I like 23mm tires on 20+mm internal width rims. The external width is irrelevant to the question.

They push out to about 25mm and at 80 PSI ride like tubulars and I'm not really exaggerating. Maybe not exactly, but awfully close.

I'm never going back to a narrower rim and could be convinced to go even wider.

I wonder when 22-23mm internal rims might make an appearance.