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Will that tire fit that rim? Reading the ISO/ETRTO numbers
After reading this you will be able to tell whether a specific tire can mount on a specific rim, using three numbers: the bead seat diameter, the internal rim width, and whether the rim is hooked or hookless. The page also shows you how to find each one on your own equipment, including on a rim with no legible marking.
Your rim is marked 622 x 19C. Your tire is marked 700 x 35C. Those two markings use different systems, and the only way to compare them is to convert both to the ISO/ETRTO form: width in millimeters, dash, bead seat diameter in millimeters. Do that and the tire is 35-622 and the rim is a 622mm bead seat, 19mm internal. The diameters match, and 35mm is inside the published width range for a 19mm internal rim. It should mount. The pressure question turns on whether the rim has bead hooks. If that 622 x 19C is a genuine ISO marking, the C has already answered it, because C is the ISO code for a crochet rim. If your rim carries no such marking, that is the one thing on this page you cannot settle by yourself.
The short answer for 622 x 19C and 700 x 35C
Three checks, in order. First, diameter. Schwalbe states that in French notation the letter at the end indicates the inside diameter of the tire, and that C stands for 622mm. So 700 x 35C is a 622mm bead seat tire, written 35-622 in ETRTO form. Your rim's first number is already 622. Michelin states the rule plainly: the bead seat diameter must match exactly between tire and rim. It does here.
Second, width. Schwalbe uses this exact pair as its worked example — a 37-622 tire fits a 622 x 19C rim. Your 35mm tire is narrower than that example, and the recommended-combination chart reproduced on Sheldon Brown's tire sizing page, credited there to Georg Boeger, lists 28, 32, 35, 37, 40 and 44mm tires against a 19mm internal rim. 35 is in that row.
Third, pressure. On a crochet (hooked) rim, the tire's own stated maximum applies, subject to whatever the wheel maker publishes. On a hookless or straight-side rim a much lower ceiling applies and the tire must be tubeless-ready. A rim marked in ISO form tells you which you have. A rim with no ISO marking does not, and that is worth resolving before you inflate anything.
Why the letter C appears twice and means two different things
This is the specific trap in your two markings. In 700 x 35C, the C is the French diameter letter, and Schwalbe states it stands for 622mm. In 622 x 19C, the C is the ISO 5775-2 rim type code for a crochet-type rim, and 19 is the internal width in millimeters. Same letter, same wheel, two unrelated meanings. Reading 622 x 19C as "a 700C rim" happens to land on the right diameter by coincidence, but it is not what the marking says.
That second meaning is more useful than it first appears. The ISO 5775-2 rim type codes are C for crochet, SS for straight side, TSS for tubeless straight side and HB for hooked bead. Inferred from that: a rim whose ISO-format marking ends in C is declaring itself a crochet rim — a hooked rim. Take that as the answer. The qualification is not that the code is unreliable, but that not every rim carries one: markings wear off, rim tape covers them, some manufacturers use their own scheme instead, and a rebuilt wheel may not be what its rim stamp suggests. If you have a legible ISO marking, you have your answer. If you do not, see the last section.
Do not assume an older wheel must be hooked. ENVE states it introduced its hookless design in 2016 and has since completed more than a thousand tests, so hookless is not confined to this season's wheels.
Bead seat diameter is the number that governs
Everything else on this page is secondary to the diameter match. Sheldon Brown's tire sizing reference explains why the older labels stopped being reliable: tires and rims evolved away from the measurements their names described, so a tire sold as 26-inch could measure well under 26 inches. Schwalbe puts the consequence bluntly — 559mm mountain, 571mm triathlon and 590mm Dutch touring rims have all been labeled 26-inch. Three incompatible sizes, one label.
If your rim has no legible diameter marking, you can measure it. Sheldon Brown's rim sizing page says to lay a tape or ruler across the rim and take the largest measurement between two points directly opposite one another, and states that the rim's measured diameter will generally be about 10mm larger than the ISO bead seat diameter. Inferred from that rule: a rim measuring roughly 632mm across is a 622 bead seat. Measure, subtract about 10, and find the nearest row in the table below.
| Bead seat diameter (mm) | Commonly labeled | Where confirmed |
|---|---|---|
| 635 | 28 x 1 1/2, 700B | Sheldon Brown; Michelin (700B) |
| 630 | 27-inch | Sheldon Brown; Michelin (27-inch) |
| 622 | 700C, 29-inch, modern 28-inch | Sheldon Brown; Michelin; Schwalbe (French C = 622mm) |
| 599 | 26 x 1.25, 26 x 1.375 (old US) | Sheldon Brown |
| 590 | 26 x 1 3/8, 650A | Sheldon Brown; Schwalbe (Dutch touring, labeled 26-inch) |
| 584 | 650B, 27.5-inch, 26 x 1 1/2 | Sheldon Brown; Michelin |
| 571 | 650C, 26 x 1, 26 x 1 3/4 | Sheldon Brown; Michelin; Schwalbe (triathlon, labeled 26-inch) |
| 559 | 26-inch mountain, 26 x 1.00-2.125 | Sheldon Brown; Michelin; Schwalbe |
| 540 | 24 x 1 1/8, 24 x 1 3/8 (E.5) | Sheldon Brown |
| 507 | 24-inch, 24 x 1.5-2.125 | Sheldon Brown |
| 451 | 20 x 1 1/8, 1 1/4, 1 3/8 | Sheldon Brown |
| 406 | 20-inch, 20 x 1.5-2.125 | Sheldon Brown |
| 349 | 16 x 1 3/8 | Sheldon Brown |
| 305 | 16 x 1.75-2.125 | Sheldon Brown |
The width range for your internal rim width
Schwalbe and WTB both publish tire-width against internal-rim-width charts, but both publish them as images, so this page does not transcribe them. The chart below is the one reproduced in text on Sheldon Brown's tire sizing page and credited there to Georg Boeger. Cross-check it against your own tire maker's chart before you buy.
| Internal rim width | Listed tire widths |
|---|---|
| 13 | 18, 20, 23, 25 |
| 15 | 23, 25, 28, 32 |
| 17 | 25, 28, 32, 35, 37 |
| 19 | 28, 32, 35, 37, 40, 44 |
| 21 | 35, 37, 40, 44, 47, 50 |
| 23 | 40, 44, 47, 50 |
| 25 | 44, 47, 50, 54, 57 |
The page carries its own caution about that chart: it may err a bit on the side of caution, and many cyclists use slightly wider tires with no problem. Treat a combination just outside a row as a question for your tire and wheel makers rather than a flat no.
The same page gives a rule of thumb: tire width between 1.45 and 2.0 times the internal rim width. Applied to your 19mm rim, 19 x 1.45 = 27.55 and 19 x 2.0 = 38, so roughly 28 to 38mm, which brackets your 35mm tire. It also names the failure modes at each extreme — a very narrow tire on a wide rim risks pinch flats and rim damage from road hazards; a very wide tire on a narrow rim risks sidewall or rim failure and causes very sloppy handling at low speeds.
There is a second self-check on the same page for a tire you already own. Pull the beads apart and measure the total width from bead to bead: it should be approximately 2.5 times the tire's ISO width. For a 35mm tire that is about 87.5mm. A tire that measures far off this is not labeled the way the chart above assumes.
To find your own internal width, WTB defines it as the narrowest point between the bead hooks on the walls that hold the tire, and names its rims by it — i25 means 25mm internal. Many manufacturers follow the same convention, so the number is often already in the rim's product name. If yours is not, the measurement is straightforward: Wikipedia's summary of ISO 5775 describes the nominal width of a rim as the inner width between the straight sides or beads, as one can easily measure it with a caliper. Take the tire off and put a caliper across the inside of the rim at its narrowest point.
Nominal width is not fitted width
A tire's printed width is measured on one specific rim. Continental publishes what happens on others. Its nominal 28mm Grand Prix 5000 S TR measures 26.4mm on a 15c rim, 27.2mm on 17c, 28.0mm on its 19c measuring rim, 28.8mm on 21c and 29.6mm on 23c. Its nominal 25mm Grand Prix 5000 measures 24.7mm on 13c, 25.5mm on its 15c measuring rim, 26.3mm on 17c, 27.1mm on 19c and 27.9mm on 21c.
Inferred from those two published sets: each gains 3.2mm across 8mm of rim width, so roughly 0.4mm of fitted width per millimeter of extra internal width. That is a Continental figure for Continental tires, not a universal constant, but it is the right order of magnitude to carry into a clearance calculation. DT Swiss describes the same effect in general terms: if the same tire model is used on rims of different widths, the effective cross-section of the tire is altered, as is the tire support. The width on the sidewall is a starting point, not a measurement of your wheel.
Hookless and straight-side rims: the hard pressure ceiling
Schwalbe states that hookless or straight-sided rims may only be combined with tires marked TLE or TLR — Tubeless Easy or Tubeless Ready — and that the official ETRTO designation for a tubeless hookless rim is TSS, Tubeless Straight Side. Schwalbe publishes the full ETRTO figure set by tire width.
| Tire width (mm) | Max pressure (bar) | Approx. psi |
|---|---|---|
| 18-24 | 5.5 | 80 |
| 25-29 | 5.0 | 72.5 (ENVE's stated figure) |
| 30-34 | 4.5 | 65 (ENVE's stated figure) |
| 35-39 | 4.0 | 58 |
| 40-44 | 3.5 | 51 |
| 45-54 | 3.0 | 44 |
| 55-64 | 2.5 | 36 |
| 65-74 | 2.0 | 29 |
| 75-84 | 1.5 | 22 |
Read that table as a ceiling set by the standard, not as the limit of what a given wheel has been tested to. ENVE describes the ISO 4210 requirement — a tire must hold 110 percent of its maximum pressure for five minutes — as widely known to be an inadequate test, and states that for a 28mm tire to reach its own approved list the tire must achieve 120 psi, or 165 percent of the stated ETRTO/ISO maximum of 5 bar. Some wheel makers test well beyond the published figure. That is a reason to consult your own wheel maker, not a reason to inflate past the table.
Zipp states that its TSS wheel and tire systems should never be inflated above 5 bar / 72 psi, that TSS rims are not compatible with tires requiring a minimum pressure higher than that, and that it limits 303 XPLR wheels to tires between 40 and 60mm. Schwalbe notes that many rim and wheel makers recommend a minimum tire width of 28mm on hookless, so that the required low pressures can be ridden without problems.
When numbers conflict, Continental gives the resolution rule: the lowest value is the one to follow. Its worked example is a 28-622 where the tire maker says 6 bar and the rim maker allows 7 — the lower figure, 6 bar, governs. Schwalbe says the same thing from the other direction: if the rim's stated maximum is lower than the tire's, the rim's maximum must be complied with, even when a higher number is printed on the tire.
On your 35mm tire specifically: if the rim turns out to be hookless rather than crochet, the Schwalbe/ETRTO table above puts the ceiling at 4.0 bar — or your wheel maker's own stated maximum if that is lower, which by the lowest-value rule above is the figure that actually governs. The tire must also carry a TLE or TLR marking. That is a very different situation from a hooked 19C rim, and it is the field worth confirming before you order.
Where these standards are actually enforced
In UCI-sanctioned competition these are enforceable rules rather than guidance. The UCI reminds teams and riders of the requirement set out in Article 1.3.018 of its regulations, which imposes compliance with ISO 5775-2:2021 and ISO 5775-1:2023, and points to Article 1.3.002 as also referring to those standards. Outside racing, ISO 5775 is a voluntary consensus standard and nothing here is legally binding on you as a buyer. It still governs what fits, because manufacturers design to it. The UCI also acknowledges that manufacturers have based compatibility recommendations on ETRTO guidance which has not always aligned with ISO. That gap is why a tire maker's chart and a wheel maker's chart can disagree, and why the lowest-value rule matters.
What a diameter and width match does not tell you
It tells you the tire will mount on the rim. It says nothing about whether the wheel will turn inside your frame or fork. Frame clearance is not covered by ISO 5775. DT Swiss puts it directly: not every frame is suitable for wide rims and tires, and it is worth asking the bike manufacturer the maximum tire width suitable for the frame. That number lives in your frame's own specification, not on the tire or the rim. If you are working from a manufacturer geometry or specification table, the frame sizing guide covers how to read one. Wheel compatibility also has a second half this page does not cover — whether your cassette fits the freehub body — and the cassette and freehub guide covers identifying yours.
Check these four fields on your own equipment
- The ETRTO number moulded into the tire sidewall, in the form 35-622. If you can only find a French or inch label, convert it using the diameter table above, and confirm against the tire maker's own size chart.
- The rim's bead seat diameter, from its stamped marking or the wheel manufacturer's specification. If neither is available, measure across the rim and subtract about 10mm, then match the nearest row in the diameter table.
- The internal rim width. It is often already in the rim's product name — i25 means 25mm. If not, take the tire off and measure the narrowest point between the rim walls with a caliper.
- Hooked or hookless. A legible ISO-format marking answers this on its own: C is crochet (hooked), SS is straight side, TSS is tubeless straight side, HB is hooked bead. If there is no such marking, this is the one field you cannot settle from the rim itself — get it from the wheel manufacturer's specification, or from the bike maker if the wheels came fitted. If it turns out to be hookless, ask for the approved-tire list and the stated minimum and maximum tire widths before you buy. Zipp publishes one; so do other wheel makers.
Every figure above is attributed to the manufacturer, standards or reference page it came from, each opened on 22 September 2026. Where a number depends on your exact model, the page names the field to look up rather than guessing it for you. Fitting and inflating tires affects rider safety; follow your wheel and tire manufacturer's own procedure.
Check it on your own equipment
These take you to the manufacturers and standards bodies the page draws on, so you can look up your exact model.
- Official support page
Zipp hookless (TSS) tire compatibility list (opens in a new tab)SRAM/Zipp's page listing TSS-compatible tires, most as reported by the tire manufacturers themselves, with double-checkmark entries dual-validated by Zipp and the tire maker together. Zipp states that under ISO standards fitment is the tire manufacturer's responsibility, and that the list is not exhaustive. Also carries the 5 bar / 72 psi never-exceed limit and the 40-60mm width limit on 303 XPLR. Use it as the model for the document to request from whoever made your wheels. — www.sram.com - Manufacturer specification
Schwalbe: tire dimensions and rim combinations (opens in a new tab)Schwalbe's statement of the diameter-matching rule with the 37-622 on 622 x 19C example, the rule that hookless and straight-side rims take only TLE/TLR tires, and its tire-width by inner-rim-width combination chart (published as an image, with a PDF download). — www.schwalbe.com - Manufacturer specification
Continental: tire/rim combinations and ETRTO standards (opens in a new tab)Continental's published fitted widths for the 28mm GP5000 S TR across 15c-23c rims and the 25mm GP5000 across 13c-21c, each with its measuring rim named, plus the rule that the lowest stated pressure value governs when tire and rim makers disagree. — www.continental-tires.com - Standards reference
Sheldon Brown: how to measure an unmarked rim (opens in a new tab)The measuring procedure for a rim with no legible marking: where to lay the tape, how to convert a circumference measurement, and the rule that measured rim diameter runs about 10mm above the ISO bead seat diameter, with a table to match your result against. It covers diameter only, not rim width. — www.sheldonbrown.com
What this page does not tell you
- Every figure is a compilation of what manufacturer, standards and reference pages state.
- The page cannot tell you whether an unmarked rim is hooked or hookless. No source consulted here gives a reliable way to judge that by eye, and ENVE states it has built hookless rims since 2016, so age is not a guide either. Where the rim carries no legible ISO marking, the answer has to come from the wheel or bike manufacturer.
- The tire-width by rim-width table is the chart reproduced on Sheldon Brown's tire sizing page and credited there to Georg Boeger. It is a third-party recommendation, not an ISO or ETRTO document, and the page hosting it notes it may err on the side of caution. Schwalbe and WTB publish their own charts but only as images, so this page does not transcribe them and instead links to them.
- The full text of ISO 5775-1:2023 and ISO 5775-2:2021 is sold by ISO and was not purchased. Statements about the standards' content come from Wikipedia's article on ISO 5775, from the UCI press release citing them, and from manufacturer pages describing them. The SS and HB rim marking formats rest on the Wikipedia article alone; the crochet 'C' format and the TSS designation are independently confirmed by Schwalbe and Zipp.
- The UCI requirement cited here binds teams and riders in UCI-sanctioned competition. It is not consumer law, and nothing in the sources consulted makes ISO 5775 legally binding on a private buyer.
- Pressure figures are stated maxima from manufacturers, not a recommendation of what to run. Appropriate pressure depends on rider weight, tire volume, rim and surface, and is outside this page's scope.
- Continental's measured-width figures are for two named Continental tires. They should not be applied to other brands or models. The 0.4mm-per-millimeter figure derived from them is Continental's own data, not a universal rate.
- The Michelin and Schwalbe pages are English translations. Schwalbe's English text says the inner tire diameter must match the 'rim shoulder diameter' where Michelin says 'bead seat diameter'. Both describe the same dimension.
Sources
Manufacturers revise specifications. Every source below is dated — open it before you buy.
- The ETRTO size designation is width in millimeters and the inner diameter of the tire in millimeters, as in 37-622.
- Michelin gives the same ETRTO format with the examples 23-622, 25-622 and 47-622, stating the first figure is tire width in millimeters and the second three-digit figure relates to the rim's seat diameter.
- The ETRTO bead seat diameter, the second number, must match exactly between tire and rim.
- Schwalbe states the inner tire diameter must match the rim shoulder diameter, and gives the worked example that a 37-622 tire fits a 622 x 19C rim.
- In French notation such as 700 x 35C, the letter at the end indicates the inside diameter of the tire, and C stands for 622mm.
- A tire marked 700 x 35C is therefore 35-622 in ETRTO form, and its bead seat diameter matches a rim marked 622 x 19C.
- Rim diameters of 559mm (mountain), 571mm (triathlon) and 590mm (Dutch touring) have all been labeled 26-inch.
- Inch and French designations became unreliable because tire and rim construction changed while the names stayed, so a tire sold as 26-inch could measure considerably less than 26 inches.
- ISO bead seat diameter 622 corresponds to 700C, 29-inch and modern 28-inch labels.
- ISO 635 corresponds to 28 x 1 1/2 and 700B; 630 to 27-inch; 584 to 650B and 27.5-inch; 571 to 650C; 559 to 26-inch mountain; 507 to 24-inch; 406 to 20-inch.
- ISO 599 corresponds to old US 26 x 1.25 and 26 x 1.375; 590 to 26 x 1 3/8 and 650A; 540 to 24 x 1 1/8 and 24 x 1 3/8 (E.5); 451 to 20 x 1 1/8, 1 1/4 and 1 3/8; 349 to 16 x 1 3/8; 305 to 16 x 1.75-2.125.
- Michelin's conversion table lists the 630 sizes under a plain 27-inch heading; it does not describe them as vintage.
- To find the bead seat diameter of an unmarked rim, lay a tape or ruler across the rim and take the largest measurement between two points directly opposite one another; the rim's measured diameter will generally be about 10mm larger than the ISO bead seat diameter.
- A rim measuring roughly 632mm across is a 622mm bead seat rim.
- ISO 5775 has two parts: Part 1 covering tires, last updated 2023, and Part 2 covering rims, last updated 2021.
- Under ISO 5775-2 rims are marked with nominal diameter and internal width separated by a cross, with a type code: crochet (C), straight-side (SS), tubeless straight-side (TSS) and hooked-bead (HB). The example markings given are SS 400x20, HB 422x25 and 620x13C.
- Standard crochet rim internal widths under ISO 5775-2 are 13C, 15C, 16C, 17C, 19C, 21C, 23C and 25C millimeters.
- The C in a rim marking such as 622 x 19C is the ISO 5775-2 crochet type code, which is a different thing from the C in the French tire size 700 x 35C, where C denotes a 622mm diameter.
- A rim whose ISO-format marking ends in C is declaring itself a crochet, or hooked, rim.
- The nominal width of a rim is the inner width between the straight sides or beads, and can be measured with a caliper.
- A chart reproduced on Sheldon Brown's tire sizing page, credited there to Georg Boeger, lists for each internal rim width the tire widths considered a safe combination: 13mm rim with 18-25mm tires; 15mm with 23-32mm; 17mm with 25-37mm; 19mm with 28-44mm; 21mm with 35-50mm; 23mm with 40-50mm; 25mm with 44-57mm.
- A 35mm tire is listed as a valid combination for a 19mm internal rim width.
- The Boeger chart carries a note that it may err a bit on the side of caution, and that many cyclists use slightly wider tires with no problem.
- A general guideline is that tire width should be between 1.45 and 2.0 times the internal rim width.
- Applying the 1.45 to 2.0 multiplier to a 19mm internal rim gives 27.55mm to 38mm, a range that contains a 35mm tire.
- If you pull a tire's beads apart and measure the total width from bead to bead, it should be approximately 2.5 times the tire's ISO width.
- For a 35mm tire, the bead-to-bead width should be approximately 87.5mm.
- A very narrow tire on a wide rim risks pinch flats and rim damage from road hazards; a very wide tire on a narrow rim risks sidewall or rim failure and causes very sloppy handling at low speeds.
- Inner rim width is the narrowest point between the bead hooks on the walls that hold a tire on the rim, and WTB names its rims by that measurement, so i25 means a 25mm inner rim width.
- Schwalbe and WTB publish their tire-width by inner-rim-width combination charts as images rather than text.
- A nominal 28mm Continental Grand Prix 5000 S TR measures 26.4mm on a 15c rim, 27.2mm on 17c, 28.0mm on its 19c measuring rim, 28.8mm on 21c and 29.6mm on 23c.
- A nominal 25mm Continental Grand Prix 5000 measures 24.7mm on a 13c rim, 25.5mm on its 15c measuring rim, 26.3mm on 17c, 27.1mm on 19c and 27.9mm on 21c.
- Across Continental's two published sets, fitted width increases by roughly 0.4mm for each additional millimeter of internal rim width.
- Using the same tire model on rims of different widths alters the effective cross-section of the tire and its support.
- When the tire maker's and rim maker's stated pressure limits differ, the lowest value is the one to follow.
- Schwalbe states the same rule from the rim side: if the rim's stated maximum pressure is lower than the tire's, the rim's maximum must be complied with.
- Hookless or straight-sided rims may only be combined with tires marked TLE or TLR (Tubeless Easy / Tubeless Ready).
- The official ETRTO designation for a tubeless hookless rim is TSS, Tubeless Straight Side.
- Schwalbe publishes maximum air pressures for TLE/TLR tires on hookless or straight-side rims, stated as in accordance with ETRTO: 5.5 bar for 18-24mm, 5.0 for 25-29mm, 4.5 for 30-34mm, 4.0 for 35-39mm, 3.5 for 40-44mm, 3.0 for 45-54mm, 2.5 for 55-64mm, 2.0 for 65-74mm and 1.5 for 75-84mm.
- The psi equivalents of Schwalbe's bar figures are approximately 80, 72.5, 65, 58, 51, 44, 36, 29 and 22 psi.
- ENVE independently states the ETRTO/ISO hookless maximum as 72.5 psi / 5 bar for 25-29mm tires and 65 psi / 4.5 bar for 30-34mm tires.
- ENVE describes the ISO 4210 requirement that a tire hold 110 percent of its maximum pressure for five minutes as widely known to be an inadequate test, and requires a 28mm tire to achieve 120 psi, or 165 percent of the stated ETRTO/ISO maximum of 5 bar, to reach its own approved list.
- ENVE states it introduced its hookless design in 2016 and has since completed more than a thousand tests.
- Zipp states that its TSS wheel and tire systems should never be inflated above 5 bar (72 psi), and that TSS rims are not compatible with tires requiring a minimum pressure higher than 5 bar (72 psi).
- Zipp limits tire size compatibility on 303 XPLR wheels to tires between 40 and 60mm.
- Zipp states that under ISO standards tire fitment with ISO compliant rims is the responsibility of the tire manufacturer; single-checkmark entries on its list are compatibility as reported by the tire manufacturers, double-checkmark entries are dual-validated by Zipp and the tire maker, and the list is not exhaustive.
- Many rim and wheel manufacturers recommend a minimum tire width of 28mm on hookless rims so that the required low pressures can be ridden without problems.
- If the reader's rim is hookless rather than crochet, a 35mm tire falls in the 35-39mm row and the stated ETRTO maximum is 4.0 bar; a lower figure published by the wheel maker would govern instead.
- The UCI reminds teams and riders of the requirement set out in Article 1.3.018 of its regulations, which imposes compliance with ISO 5775-2:2021 and ISO 5775-1:2023, and points to Article 1.3.002 as also referring to those standards.
- The UCI requirement applies to teams and riders in UCI-sanctioned competition, not to the general public; outside racing ISO 5775 is a voluntary consensus standard.
- Manufacturers have based compatibility recommendations on ETRTO guidance which has not always been aligned with ISO standards.
- Frame clearance is not settled by matching bead seat diameter and rim width; the maximum tire width a frame accepts must come from the bike manufacturer.