What is the maximum or minimum tire width I can fit on my bicycle

The minimum is dictated by the width of the rim. Sheldon Brown has tables, here: https://www.sheldonbrown.com/tyre-sizing.html

The maximum size depends on the space between the stays at the rear and the width of the brakes and the space under the mudguards where the tyre has to fit. This has to allow for the dynamic shape changes the tyres undergo while you're riding and for mud or debris sticking to the tyre itself, if you don't want to be thrown off the pony by a locking wheel.

These are no laws of Nature. If the size works it's OK.

In practical terms, people usually seem to ask this question because they need to replace a tyre on their bike but can't find tyres in exactly the same width as the one they already have. Unless the existing tyre was close to the limit of what will fit, using a slightly different width (e.g., and eighth or tenth of an inch, or a couple of millimetres) is going to be fine.

Another gotcha is the fit of other parts around the tyre.

Rim brake arms and calipers can change their profile throughout their stroke, and their stroke can change as the pads wear down.

V brake arms are pulled in toward the side of a tyre as you brake. So a close fit here can mean interference once they close up. This would be exacerbated by worn down brake pads.

I personally have a 28mm tyre with a shimano 105 rear rim brake where the underside of the caliper's arms touch the tyre if my inner brake cable is slackened-off. Mind you I can'f refit that rim if it has an inflated tyre, so tolerances are quite tight.

Mudguards/Fenders can have a problem with larger tyres too - though these are generally quite adjustable.

Toe Strike Slightly unusual, but if you're going to aggressively knobbly tyres then its possible for your toe to clip the knobs while turning. If you had smoother tyres, then catching the knobs with your shoe can catch where the original tyres might just rub.

I have never utilized a formula, or some all-purpose rule for determining tire width. often I rely on frame manufacturer specifications. there are too many variables, such that it's easier just to eyeball it (for me, anyways). tires can measure wider or narrower than their specified widths, and that width also changes depending on what rim it's mounted to. got a flexy frame or wheel? expect the tire to wobble on a sprint or climb, requiring buffer space on either side so it doesn't rub the frame. some brakes can have higher or lower arches, again affected by rim width or just where they mounted the bridge. is it an older tire? might be wider than it used to be.

if you want a more empirical method, use spare wheels and just measure the gap between rim and frame. tire width is roughly gonna be the height of the tire too (not accounting for tread). it's a pretty rough measurement but it'll give an approximation at least, and when mounting tires it should never come down to the millimeter anyways. just don't forget to check down by the bottom bracket as that's as often a limiting factor as the brake bridge. also factor in whether you'll be using fenders. when in doubt, size down.

one other way i used to think about it was in terms of what age and type of bike it is. i could pretty much guarantee that a hybrid bike would be able to fit up to 38c. whereas i wouldn't push it any larger than 25c on an aero or road bike (unless i specifically knew it was designed with larger tires in mind). high-end cross bikes would get 33mm because that's the biggest you're allowed to use. 26" mountain bikes could almost always take up to 2" knobby tires... there were exceptions, sure, but this worked more than it didn't.

I was investigating the source of the document on rim vs tire width in Nate W's answer. I discovered enough new information to warrant writing a new answer. Basically, the maximum tire size that you can fit on your rims is very likely larger than what's specified on the chart. The chart is based on an older specification by the International Organization for Standardization (ISO) that is in the process of revision.

While answering a different question, I referred back to this question and answer. The information there caused me to realize that the ISO standard may be a bit dated in 2020. For example, many performance road bikes made within the last 5 years come stock with 25mm tires (note: that's nominal width, i.e. the width printed on the sidewall, rather than width as measured). 25mm tires were technically out of compliance with that questioner's rims.

On further research, the tire size guide Nate cited stems from the International Standards Organization (ISO), standard 5775. That document was published in 2014/2015, and it appears to be under review at the time of writing in 2020; ISO reviews its standards every few years. The documentation of the standard is gated. However, in 2016 Bikerumor appears to have published a table based on the ISO standard, reproduced below. Note that it's similar but not identical to the documentation that Nate gave. (NB: you almost certainly have "crotchet type" rims, which have bead hooks; some modern drop bar wheels are hookless, and these would be "straight side type" in the chart.)

In the Bikerumor chart, it appears that the ISO only approved 25mm tires on rims with 13mm to 17mm internal width. However, many clincher rims in 2020 have 18 to 20mm internal width. A number of new carbon wheels from the likes of Zipp, Enve, and Roval have internal widths of at least 21mm. I have had 25mm Continental Grand Prix 4000 S-IIs mounted to rims with a 19.4mm internal diameter for at least a year, and I've never experienced a blowout (NB: these tires measure 27.6mm or so when inflated; they were notably wider than the nominal size). Worse, Zipp's 303 Firecrest wheel has an internal width of 25mm. Since it's a hookless design, it appears that the smallest tire that ISO approves would be at least 45mm in width. And yet, Zipp recommends a minimum size of 28mm.

If the ISO specs are correct, a lot of people on current generation wheels should be experiencing some sort of tire failure, and yet there doesn't appear to be a spate of such failures. So, the ISO specs are wrong. But where does that leave current riders whose tires and rims don't fall into the officially approved list?

• First, check if your wheel or rim manufacturer lists specific tire incompatibilities (e.g. Enve lists specific tires as incompatible and requires tubeless; Zipp merely requires tubeless on its 303 Firecrest and 303S, it doesn't test specific tires, and it listed a minimum width of 28mm for the Firecrest, and I believe 25mm for the 303S.) This is a relatively rare case. The manufacturers with such requirements appear (to me) to be pushing design limits in some way, e.g. much wider rims than the ISO (presumably) reviewed in 2014/15.

• If there are no compatibility specs, then for newer performance road wheels, the practical minimum tire width is likely smaller than the ISO specifications. For example, the Hed Belgium Plus and associated rims have internal widths of 21mm. For both the disc and rim versions, Hed specified a minimum tire width of 23mm and a maximum of 58mm. 23mm tires are surely fine mounted on rims with internal widths of 17-20mm, even though this appears to conflict with the ISO chart. 25mm tires, similarly, should be fine on road rims of 18mm to 20mm, despite the chart.

• I'm not certain about compatibility on modern rims for tires smaller than 23mm. But such tires are rare, anyway. An interesting side note: when Hed released the Jet aero wheels with a 21mm internal width rim, they appear to have recommended tires of at least 22mm, and they seem to have tested tires of 22 and 23mm in the wind tunnel. The Continental Attack tire may have been available in 22mm at the time of release, but it may have been re-specified as a 23mm tire. I'm not actually aware of any current road tires narrower than 23mm, although I don't specifically look for these tires.

• For wheels with internal widths over 21mm, I would avoid nominal 23mm clincher tires out of caution. This is based on an educated guess. I expect more performance road disc brake wheels to exceed 21mm internal width in the future, and 23mm tires should become less and less common anyway. (NB: This rim width would have been unheard of for road wheels in the early 2010s.)

• For 700c wheels with road tires, if you have reasonably current wheels, the maximum tire width may not be a concern. Your rims are likely to be OK with any tire that you might want to put into your frame.

• For 700c wheels with gravel tires, based on the ISO chart, the theoretical maximum width probably exceeds your frame clearance anyway. Consider that if you somehow have 700c rims with a only 17mm internal diameter on a gravel bike, ISO thinks that you can mount a maximum 52mm tire, which is a bit over 2 inches. In 2020, the largest gravel frame tire clearance for 700c tires that I'm aware of is around 50mm. Rest assured that gravel rims are trending much wider than 17mm. Ergo, gravel cyclists don't need to worry about the maximum safe tire width on their rims.

• If you have 650B rims on a gravel bike, then I would expect most of these to be well over 17mm internal diameter anyway.

I'd expect the standard to be updated soon. Hookless rims are ubiquitous in cars and current mountain bikes, but they may only just be starting to make their way to drop bar bikes, and then mostly for carbon rims. Removing the bead hook does simplify the manufacturing process, which potentially reduces cost. It also may smooth the tire/rim interface, improving aerodynamics slightly. The new ISO standard might revised to account for the tire width issues mentioned above and the advent of hookless rims on performance road bikes.

Note that the approved tire widths in the Bikeradar chart and the J&B Importer chart differ slightly, although many are similar. Bikeradar's chart lists 23mm tires as compatible with 13 to 16mm internal width rims. J&B's lists 13 to 17mm. For 25mm tires, Bikeradar's chart says 13 to 17mm rims, whereas J&B says 13 to 19mm. It's possible the charts are both based on different revisions of ISO 5775.

Finally, note that Jan Heine of Rene Herse Cycles might disagree with many of my statements above. He states that if the rims are too wide, the tire pressure won't push the bead against the bead hooks strongly enough to retain it. This could lead to tire blow out. He does admit that the ETRTO chart is conservative in this respect. He has a rule of thumb that the internal rim width should be at least 20% narrower than the tire. For a 25mm tire, this would suggest a maximum internal rim width of 20mm. Even so, this puts my main set of wheels in compliance with my usual 25mm (nominal width) tires. However, this suggests that Hed's tire width recommendations for its Jet rims, and the similar Belgium rims, are too narrow (at 21mm internal width, they should have at least 26.25mm nominal tire width by the Heine rule).