If you have a set of 2.4" tires and 3.8" tires and only use 1x rim to run either...you're always going to be suboptimal.

A 3" tire with an i40 is as narrow as I'd wanna go and there's no way I'd run a 2.4" tire on that.

 

It seems the industry is still sorting this out.

Maxxis says nothing narrower than i40 for a 3.0 (per the tag on the tires)
Stan's says i32 is good for 2.8, and i34 is fine for 3.0 (per the website)
Jones Bikes says i45-i50 is really nice for 2.4's (taken from somewhere on his site FAQ)



I personally think i40 is good for 3.0s. I have i43s and love them, but when I mounted a 2.4 to it, it went on fine, but was too square for my liking. I actually began my plus riding with 3.0s on i30s and wasn't super impressed. I'm a fan of wider is better, other's prefer narower.

I suspect that in the near future we'll start to hone in on an accepted ratio of tire/rim as the OP mentioned.

If I had to guess, I think that ratio will eventually fall between 1.8 and 2.1
For reference, that's between i36 and i43 for a 3.0.

I also have run 2.6's on i30 and thought it was really nice, but I like real plus tires.

 

The answer is always going to be "It depends". And the dependencies are your height/weight/riding style, your preferences, your past, present, and future hang-ups, the types of trails you ride, the trail/soil/snow conditions, preferred tire pressures (actual vs. measured), casing construction, and, of course, angle of the dangle.

"The industry" hasn't sorted this out, and truthfully won't. Too many options, too many people, too many preferences.

 

i.e. when in doubt by a set of each from Lace Mine 29 - Big Bicycle Wheels

 

If we convert 2.6" to mm, we get 66mm, divide that by 25mm (my current rim width) and we get a tire-to-rim-ratio (TTRR) of 2.64. The tire is roughly 2.64 times wider than the rim.

So, we can extrapolate that and say something like a 3.8 tire on a 35mm rim is TTRR of 2.74. Not that much worse.

While running a 3.8" tires on a 35mm rim wouldn't be ideal, the industry has long been running 2.3 tires (58mm) on 20mm internal rims, resulting in a TTRR of 2.9! We're already quite accustomed to big tires on little rims.

Your math of a linear growth relationship between tire width and rim width only works out if assuming that wider tires scale in every way "bigger", e.g. more volume + thicker casting. However in reality plus tires do have a significantly higher air volume surrounded by a very thin casting to keep weight increase at an acceptable range. In order to compensate the stiffness disadvantage of thin sidewalls you need an overproportional wider rim to support the tire or it will buckle under heavy loads when cornering hard. 2.4 tires still work ok on 22.5-25mm rims, a 2.6 tire will need at least a 30mm rim and a 3.0 already needs a 45mm rim, so as you can see required rim width grows much more than the actual tire width.

Theoretically you could run a 3.8" on a 35mm rim with higher air pressures to stabilise the casting but it will nullify the grip advantage and lead to a far worse problem: The bigger air volume of the plus tire acts as an undamped airspring due to its thin casting and bounces off obstacles like a basketball. Imagine I double your fork travel but equally turn down rebound damping - how would that work out for you?

Either way I'd get a 35mm wheelset which should be good for 2.5 - 2.8 tires without adding too much weight. Everything above is a failed attempt to outsmart physics and won't stay in the (mass-)market much longer for obvious reasons.

 

Opinions are like arseholes, but here is mine (opinion):
- 29mm IW rims are super common and good for 2.3-2.6, and I've found 2.8 OK on them too.
- 35mm would therefore step up a bit and prob be 2.5-3.0, however I'm not sure 2.3s would be too nice on them
- All of them have an element of uncertainty, and keep in mind that plenty of Maxxis 2.3s will measure at 2.2" and Schwalbe 2.3s at 2.4".

 

I've had the same question in my head lately. For the last few years I have been running Stans arch EX rims with an i19 with Maxxis ardent 2.4s. I ran those for a couple years and never burped once and never had a problem tubeless. In fact two years ago in Colorado I had to drop my psi down to 7 front and back in order to ride the trail around Leadville without sinking through the snow.

Last winter I built a new set of wheels using the same hubs. I bumped up to Stans Flow ztr with i29. I will say the 2.4 looks so much better on this rim. Now my question is how big of a tire can I go with these new wheels. Stans recommends up to 2.8 so I'll go with that even though I haven't tried it yet.

 

Funny,

I was just reading that American Classic Smokin Gun 40mm internal rims are were designed with 2.5-3.0 tires in mind.

I could probably be really happy with the variety of high-volume, low weight 2.4-2.5 tires on the market, as long as they'd fit my narrow chainstays with 40mm rims. Err, this would be on my big travel Meta, which would rarely be equipped with such a wheel.

Currently I've got a Specialized Slaughter 2.6 on 25mm internal rims that's about as big as I can go. I've run a worn Breakout 2.5 on the same rim and it's a hair smaller. I'd probably need to stick with 2.4's if I was going to run them on 40mm rims, which means I'll need some heavily reinforced rear tires.

The 40mm rims would spend most of their lives on my new hardtail which I think would be good fun 3.25" Crux or 3.5" Hodag.

 

I don’t really have any mathematics to back this up, only real world testing done mainly on my Waltworks Ultimate Warrior.

I run 3.8” Hodags on 45mm rims and find them to work nicely. True width is a smidge over 3.6” on those rims. I could go wider of course but for the time I use this setup my Arc 45 wheels are more than up to it.

When I built my first 29+ wheels I used 35mm rims (Arc 35) and they were fine with Chupacabra but I now use 45mm LB rims and the profile is much squarer and the tyres just work better in all instances.

I run 2.4 and 2.5WT tyres on 28mm Reynolds rims on my Pivot and really like them but I’ve also used them on my 30mm LB’s and 35mm wide Arc 35 rims where they are obviously only very slightly wider.

2.6 Schwalbes work very nicely on 36mm Ibis 741’s and I have also used 2.25” Bontrager SE4 tyres on those rims with success although the SE4’s are much wider than advertised.

Hope this helps a little bit.

 

I'm trying a 2.8 rekon on a 50mm width rim right now. So far I like it and see no downside yet.

Sent from my SM-G900V using Tapatalk

 

Well, there have always been some "rules of thumb" to follow on this.

It's always been said that your tire width should not exceed 2x your rim width. For example, 19mm rim = max tire width of 38mm, etc...

Conversely, the tire width should never be smaller than your rim width. On a road bike, for example, a 23mm road slick should never be mounted to, say, a 25mm rim. Just common sense...

But ya, in a lot of cases (as is true with almost all the tire questions) the answer is going to be it depends. (see above).

 

Well, there have always been some "rules of thumb" to follow on this.

It's always been said that your tire width should not exceed 2x your rim width. For example, 19mm rim = max tire width of 38mm, etc...

Conversely, the tire width should never be smaller than your rim width. On a road bike, for example, a 23mm road slick should never be mounted to, say, a 25mm rim. Just common sense...

But ya, in a lot of cases (as is true with almost all the tire questions) the answer is going to be it depends. (see above).

Are you talking external or internal rim width???

19mm internal rim width is standard on 559 or 26" rims. Standard 26 x 1.95 inch tire width is 49.5 mm. 49.5/19 = 2.6 tire to rim ratio. The standard is between 2.0 to 3.0x tire to rim width. Am I missing something?

https://www.bikerumor.com/2016/08/12/tech-story-match-bicycle-tire-width-rim-width-best-results/

Is this story wrong? They are saying it's worse to go under 2x tire to rim width than it is to go over 3x tire to rim width.

There is no consensus on what the optimal rim width is on 2.5 inch wide tire or greater. But for 1.1 inch to 2.4 inch tires, it's accepted that they all can fit on a 19mm internal width rim on the chart above. 28/19 minimum is 1.5x tire to rim ratio, and 62/19 is 3.3x max recommended tire to rim ratio. Average is 2.4x. There are people on here that have gone 3.5x and say they have zero problems. According to the article:

"It is primarily based on experience, testing, and feedback from our customers as well as the professional athletes we work with. The basics are that if you run a rim that is too wide for a particular tire you have a lot more issues with tire and rim damage, as the rim is much more likely to bottom out on lateral rock impacts causing tire or rim damage. Conversely, if the tire is too wide for a given rim, you get more tire roll due to the larger casing size and higher aspect ratio of the tire, which together create more leverage on the tire allowing the casing to collapse and roll over the rim during hard cornering."

I am just a dumb beginner, but to me the above translates as too wide is the lesser of the two evils compared with too narrow. And just my opinion but a wide + tire that's two pounds with thick sidewalls should do just fine on a relatively narrow rim. I'm doing 27.5 x 2.5 on a 23 mm internal width rim (2.8x ratio) and it's fine, it's actually great. I've crashed once in 8 months with this front tire. Thin sidewall tires are thin width to begin with so there is no issue. Wider tire = thick sidewall = still OK for cornering because the wall will not collapse like a thin walled tire might. It all balances out.

 

Depends, yup got me some, and Depending on the day's ride, it shall dictate size and weight......of course that Depends.

 

rim to tire width ratios for plus tires

3.0 tire on i50: 1.52
3.0 tire on i45: 1.68
3.0 tire on i40: 1.90
2.8 tire on i50: 1.42
2.8 tire on i45: 1.57
2.8 tire on i40: 1.77
2.8 tire on i35: 2.02
2.6 tire on i45: 1.46
2.6 tire on i40: 1.65
2.6 tire on i35: 1.88
2.6 tire on i30: 2.20

For comparison, here are common rim widths for normal tires:

2.4 tire on i30: 2.03
2.4 tire on i28: 2.17
2.4 tire on i25: 2.44
2.3 tire on i30: 1.93
2.3 tire on i28: 2.17
2.3 tire on i25: 2.44

keep in mind that plus tires have more air volume compared to regular tires. doing a straight comparison to regular tire ratios, a 3" tire should be on an i40, a 2.8" on an i35, and a 2.6 on an i30. imo, those should be minimums, and maximums will be dictated by tire design. imo, id add 5mm to each rim width for each tire and call that ideal. ie, 3" = i45, 2.8 = i40, 2.6 = i35.

 

rim to tire width ratios for plus tires

3.0 tire on i50: 1.52
3.0 tire on i45: 1.68
3.0 tire on i40: 1.90
2.8 tire on i50: 1.42
2.8 tire on i45: 1.57
2.8 tire on i40: 1.77
2.8 tire on i35: 2.02
2.6 tire on i45: 1.46
2.6 tire on i40: 1.65
2.6 tire on i35: 1.88
2.6 tire on i30: 2.20

.

I'd slim this down and edit a bit to :

3.8 tire on i50:
3.25 tire on i50:
3.25 tire on i45:
3.0 tire on i40:
2.8 tire on i40: 1.77
2.8 tire on i35: 2.02
2.6 tire on i35: 1.88
2.6 tire on i30: 2.20

But that's just me

 

Maybe a better thread for this feedback...

Been riding 27.5+ 45i Scrapers with various WTB 3.0 tires.
Getting ready to build a new Wheelset and am torn between two rims.

WTB 45i Scrapers
DT Swiss 40i XM551

Love some thoughts from anyone who's ridden both or ridden 40i rims with 3.0 tires.
thanks

 

I am looking at the same two rims. Which way did you end up going?

 

Barnetts Manual for rim measuring

This should help clear things up :thumbsup:

Determine size of new tire by one or all of
following choices:
[ ] Look on sidewall of tire or molded in edge of
tread for nominal size description. Enter
here: __________
[ ] Look on sidewall of tire or molded in edge of
tread for ISO size description. Enter here:________

38. [ ] Measure width from bead-to-bead (edge-toedge)
of tire (flattened as best possible) and
record width here: __________
Flattened width between beads
Cross -section of flattened tire
19.22 Flatten the tire and measure bead-to-bead to determine
flattened width.
39. [ ] Divide answer in step 38 by 2.5 to determine
"section width" and record answer
here: __________
40. [ ] Multiply rim inside width from step 37 by 1.4
to determine narrowest acceptable "section
width" and record answer here: __________
41. [ ] Multiply rim inside width from step 37 by
2.0 (road bikes) or 3.0 (MTBs) to determine
widest acceptable "section width" and
record answer here: __________
42. Check one of following choices:
[ ] Step 39 is included in range of steps 40 and
41, so tire width is ideal for rim.
[ ] Step 39 is outside of range of steps 40 and
41, so tire width is potentially unacceptable
for rim.

 

Apparently Jeff Jones was experimenting with higher volume 2.4 tires on 50mm rims back in 2013 and still likes that setup today.

I think if I ended up building a new wheelset out of some old hubs that I've got, I'd probably go 45 or 50 rim width to be able to comfortably run a 3.8 tire, and still have the ability to run a 2.6 as well.

After this weekend's bikepacking trip and getting beat up on my hardtail, lower pressures would be nice.

I think 2.6 is as small I like going anymore (nearly all "small" 275 tires have been cleared out of my garage.)

I figure if I need a long-distance fast rolling setup I'll switch to my 29x2.4 Ardents.

 

IAMTHRILL, its so complicated, just to say that inner rim width should be in range 20..29% relative to flattened tire width, or 13..29% for MTB.
IMHO, that MTB special case is not more than legacy error, inherited from manufacturing process of first-gen thin MTB rims based on road rims.

PHeller, simple geometry equation has a result, that any given tire has its maximum overall diameter when tire to rim ratio TTRR=1.38 (so small!), and this point seems to be an optimal ratio, simply by the purpose of pneumotire. At least, for round slick tires, when its shape is not depend on TTRR.
So, i45 rim may be ideal (and widest possible) for 2.4 - 2.5 tire and acceptable (but far from ideal) for 3.8 tire.
My preference is i58 for 3.0 WTB Rangers, for example.
But for knobbies all goes differently. See manufacturer specs, to avoid square or folded-in-half profile of tire tread.

 

theres no reason to slim it down as its meant as a comparison, not an opinion. i agree with your opinion (even though i run i45s with a 3" tire) but i wanted ppl to see for themselves and make thier own decisions.

 

me likey your listing for general fitment purposes. :thumbsup:

 

I just recently bought a decent 32spoke boost oem wheelset with WTB Scrapper 40mm rims for 120€ from on-one bikes UK.

A second wheel (or wheelset) has the huge advantage of quickly swapping between tire widths fast, I consider 30mm rim good for 2.6" maximum width, if you want 2.8" a 35mm rim is perfect.

 

The new WT trail standard is 35 mm ID

that seems to be perfect for the new Maxxis line of WT wide tire standard

 

I think I'd be more interested to know about the number of people who have encountered problems from overly large rims with "normal" tires than running overly large tires on narrow rims. We keep hearing that the sidewall is more exposed on an overly large rim, but would those tires still have torn on narrower rims? Who knows.

For instance, many folks have had really good luck with Schwalbe 2.6 tires on rims as wide as 40mm, and of course Jeff Jones loved the Ardent 2.4 on 50mm rims (which seems like a bit much).

I guess it depends on the type of tire, too. Schwalbe's Nobby Nic and Rocket Ron are both very round casings. The Ardent is also pretty round. The DHR, Slaughter, Rock Razor, Trailblazer, even to some extent the Rekon aren't as round.

I'm still stuck in this dilemma of "do I compromise the future potential to run 3.8 tires on 35/40/45mm rims for the ability to run the 2.6 tires I've got in the garage?"

Stan's even lists the i38 "Major" rim for tires from 3" to 3.5" which might cover the majority of 275x3.8 tires out there. Alternatively, Schwalbe designed the 2.6 tires for use on i30-i40mm rims.

 

I think I'd be more interested to know about the number of people who have encountered problems from overly large rims with "normal" tires than running overly large tires on narrow rims. We keep hearing that the sidewall is more exposed on an overly large rim, but would those tires still have torn on narrower rims? Who knows.

EXACTLY!!! You could in theory put a four inch wide fat bike tire on a 45mm rim. This is why no one out there has a concrete, factual + rim size chart yet. We are in uncharted waters between standard and fat bike rims right now, and probably will be for 1-3 more years before anecdotal data becomes real data.

One of these years when I get out of debt (don't ask, small business), I'll get the 'correct' rims that are around 50% of the tire's width, tubeless ready, 450g each, and all that other nice stuff for $500+/wheelset. For now, being a cheap ass by necessity and not choice, I found some interesting 23mm and 24mm internal wheelsets for under $200 that should fit plus tires OK. Wheelmaster makes some with Weinmann, DT Swiss, Alex, etc. rims for a decent price and in theory they should do just fine with a 2.8 or 3.0 tire. I found them on Amazon and other sites typing in keywords 559x24, but they have 584 and 622 as well (more actually than 559). Be careful choosing them though, the cheaper ones are often rim brake only and bolt-on instead of QR. Cheapest wheelset with disk and QR start around $125 and are narrow 19mm or 21mm; another $50 or so for 23/24mm. 25mm and above skyrockets in price for a ready-made wheelset unless you build the wheel from the rim.

2.8 = 71mm tire width / 24mm rim width = 3.0x tire to rim width.

Right now I'm doing a standard tire on a narrow rim: 2.4 = 61 mm tire width / 21 mm rim width = 2.9x tire to rim width, almost exactly the same as above.

And while I have to admit the 2.9x tire and rim ratio feels a tad floppy, they do just fine, and are a huge improvement over the skinnier front tire. I dunno how far you can extrapolate out from 2.4 inches, but $170 for a wheelset is a lot cheaper than $500+ for people on a budget that want to have a plus tire on their non-boosted bike. This would just be for the front though, back cannot take a + tire

 

For the purposes of this discussion I'm not interested in racing. You don't talk about 40mm-50mm rims and racing at the same time. Like you said, diminishing returns after 2.6 tires (which Jared Graves is running) and 35mm rims (which I'm sure a few EWS racers are using).

I've got racing wheels, that's more or less taken care of. I don't race anyway, so it doesn't matter to me.

I'm actually looking more along the lines of a wheelset for soft-condition bikepacking. Not snow, not sand, just soft. I think a lightweight bike with 27.5x3.8 tires would be rad for such conditions. On hardpack I think a 29x2.6 setup would be fine. But I don't like building a wheelset for a specific tire (3.8) because I may want to use the same wheelset for a 2.6 or 2.8.

 

I know that this is an older thread, but I've been comparing i40 vs i35 rims for 2.8 tires for a new wheel set I will be building. While there are some nice charts provided by various rim manufacturers as well as diverse opinions (from super narrow rims recommended by Stans to wide rims recommended by Derby to uber wide rims recommended by Jones), ultimately I think that in this day and age the tire manufacturers should provide for each tire the "IDEAL RIM WIDTH" specification. Teravail is now doing this to their credit and the results are very interesting! For example,

Coronado: 29 x 2.8 - ideal rim width is i35.
Coronado: 27.5 x 3.0 - ideal rim width is i45.
Cumberland: 29 x 2.6 - ideal rim width is i29.
Cumberland: 27.5 x 2.8 - ideal rim width is i45.

This is valuable! And in the comments Teravail says that you can go down or up one notch from there which seems to be a good rule of thumb.

To some extent Maxxis is doing this with their WT tires where they specify i30 to i35 for the ideal rim widths as well as some other companies.

But I think tire manufactures should agree to add the IDEAL RIM WIDTH specification for each tire offering on their websites. This would really help us average peons like myself sort out the muddled waters of tire - rim combinations in these exciting times full of experimentation.

 

I know that this is an older thread, but I've been comparing i40 vs i35 rims for 2.8 tires for a new wheel set I will be building. While there are some nice charts provided by various rim manufacturers as well as diverse opinions (from super narrow rims recommended by Stans to wide rims recommended by Derby to uber wide rims recommended by Jones), ultimately I think that in this day and age the tire manufacturers should provide for each tire the "IDEAL RIM WIDTH" specification. Teravail is now doing this to their credit and the results are very interesting! For example,

Coronado: 29 x 2.8 - ideal rim width is i35.
Coronado: 27.5 x 3.0 - ideal rim width is i45.
Cumberland: 29 x 2.6 - ideal rim width is i29.
Cumberland: 27.5 x 2.8 - ideal rim width is i45.

This is valuable! And in the comments Teravail says that you can go down or up one notch from there which seems to be a good rule of thumb.

To some extent Maxxis is doing this with their WT tires where they specify i30 to i35 for the ideal rim widths as well as some other companies.

But I think tire manufactures should agree to add the IDEAL RIM WIDTH specification for each tire offering on their websites. This would really help us average peons like myself sort out the muddled waters of tire - rim combinations in these exciting times full of experimentation.

Best rim width isn't absolute unfortunately. If you ride high speeds park terrain, rocky or shale terrain or like big jumps less rim width can be better for that terrain than if you are trail riding loose over hard at medium speeds with limited jumps. At the lower speeds you'll also be able to run lower pressures for a bigger cornering footprint.
If your terrain allows lighter sidewalls where you don't worry much about sidewall slashes you can really benefit from low smaller knob tires at low pressures on wider rims.

 

I guess I'm old school. I don't like really wide rims compared to tire size.

I had a fatbike with 26x4.0 on 100s. I hated the tire profile. On my current Farley, I like the 4.6-4.8s on Mulefut 85s.

My XC bike has WTB KOM i23s with 2.35 wide tires.

I have a 29er converted to 27.5+ and I don't particularly like the tire profile with 27.5 x 2.8 on WTB i45 Scraper rims.

For 29x3.0 I have a wheel set with WTB Frequency i25 and another that with Velocity P35 i30.8 and really like the tire profile compared to an i45 or i50 rim.

 

The answer for rim width vs tire width is not that simple...there are too many variables to have a single conversion factor for everything from 2.4 to 3.8.

For example, the aspect ratio of the tires is different i.e. height to width ratio of the actual tire. So measuring across the tire with it flattened out doesn't tell you how the tire was designed.

I have a 3.0 Maxxis High Roller on a 52mm (internal width) rim and the rim is too wide IMO. I also have a Maxxis FBR 3.8 mounted on a 35mm (internal width) rim and the rim is too narrow. That is about the only thing I can tell you for sure .

I did talk to some guys at Maxxis and they like to run their 2.8 tires on a 35i rim even though the Maxxis web site has the info below...if the format gets screwed up the chart is at the bottom of the page on each Maxxis Mountain Bike tire:

Inteded Use Tire Width (in) Inner Rim Width (mm)
XC Racing 2.00 - 2.20 20 - 25
Light Trail 2.20 - 2.40 25 - 30
AM/Enduro 2.30 - 2.50 28 - 35
2.60 35 - 40
Plus 2.80 - 3.00 40 - 45
Fat 3.80 - 4.00 70 - 80
4.80 90 - 100

 

Hi !
Quick update on this subject.
Is there a rim inner width that will suit correctly 3.0 to 3.8" tires ? 45mm ?
Other question : is there any reason why I shoudn’t mount a 27.5*3.8 tire with boost wheels (110mm front, 148mm rear) ? I mean, with a specific bespoke frame.
The idea is to find a setup in 27.5 wheels where I could shift from plus format (3.0“ tires) to (alsmost) fat format (3.8“ tires), with the same wheels.

 

I would say, the size range you are looking at would be ideal on i45's. When I bought my Sergeant V3, I opted for 70mm (i64) Alex Blizzerk 27.5's since my plan is to run 3.25-4.0 full time. The idea of i64 was tire profile for traction and flotation in adverse conditions. Rides like a plus bike even when I let the air out! Currently, I am running a pair of Crux 3.25's which do a great job of backcountry exploration. Winter, the Van Helga 4.0's go into service.

Sarge III sportin i64's and 3.8's.

 

Thanks Bansheerune and mikesee !

@mikesee : the idea would be to build a bespoke frame.
And indeed, ut’s not an update, it’s more that I would like to get updated advices on this subject
When you say that an inner width of 45mm is a compromise, do you mean that it works well on this whole range (2.8-3.8“), or it’s not a real fit for 3.8“ ? Should I go to i50 ?