1926 Stearns-Knight Tire Fitment Guide

1926 Stearns-Knight vehicles use four size designations across two model lines. The 6C uses 33X6.00 and 600-21, while the 6S uses 33X6.75 and 700-21. Every listed size is a bias-ply tire, and the listed product-bearing sizes mount on 21-inch rims. Where wheel-width guidance is available, 600-21 products are listed for 3.00- to 3.75-inch rims, and 700-21 products range from 3.00- to 4.00-inch rims depending on the tire series.

The practical takeaway is that year and make alone are not enough for a 1926 Stearns-Knight tire decision. You need to identify whether the car is a 6C or a 6S, then confirm which of that model’s two size designations is currently on the car or matches the wheel and restoration direction you are following. That keeps you from crossing over into the larger 6S sizing or assuming all 21-inch Stearns-Knight wheels used the same tire width.

On a 1926 Stearns-Knight, 33X6.00 is an antique diameter-by-section size. The first number gives the tire’s overall diameter in inches, so this tire stands about 33 inches tall, while the second number gives the nominal section width at 6.00 inches. It is a bias-ply format typical of the balloon-tire era and is associated here with the 1926 Stearns-Knight 6C.

That older naming style can be confusing because modern buyers often expect the final number to be wheel diameter. On early balloon tires, that is not how the code works. If your 6C still carries antique-format markings on the sidewall, keep that marking in mind when comparing replacements to numeric sizes such as 600-21. Matching the original size language can matter for both visual authenticity and confidence that you are staying in the right fitment family.

On a 1926 Stearns-Knight, 600-21 is a numeric bias-ply size. The 600 portion represents a nominal 6.00-inch section width, and the 21 indicates a 21-inch rim diameter. Within the 1926 Stearns-Knight range, this size belongs to the 6C. Available products in this size appear in both blackwall and whitewall forms, which gives the owner some latitude in how formal or understated the finished car looks.

Numeric balloon-era sizing is generally easier for modern buyers to read because the wheel diameter appears directly in the code. Even so, you should not assume that another 21-inch Stearns-Knight tire is interchangeable. The 6S uses a larger size family. If you are comparing an existing antique-format tire to a numeric replacement, read the sidewall carefully and make sure the size family stays with the correct model before moving on to brand or sidewall-style choices.

1926 Stearns-Knight tire sidewall choices vary by size. In 600-21, available products include Blackwall and Wide Whitewall versions. In 700-21, listed options include Blackwall, Wide Whitewall, and Double-Whitewall styles. Those choices let a car be finished with anything from a restrained touring look to a much more formal luxury presentation, especially on a make that originally competed in the upper end of the American market.

For a car being restored with close attention to period appearance, sidewall style can matter almost as much as the size itself. Blackwalls often suit a more conservative or utilitarian presentation, while wider whitewall treatments deliver a richer late-1920s visual effect. If the car will be shown, check the standards of the event or marque community you follow, since judging expectations can differ by body style, market history, and how strictly originality is being interpreted.

Four brands appear in the listed tire range for 1926 Stearns-Knight vehicles: Lester, BFGoodrich, Firestone, and Michelin. The 600-21 size is available from Lester and BFGoodrich. The 700-21 size is available from Firestone and Michelin. Each of those offerings stays within the period-correct bias-ply construction expected for a luxury American car from 1926.

Brand choice on a car like a Stearns-Knight usually comes down to the look you want, the sidewall treatment you prefer, and whether a given brand’s available series aligns with your restoration priorities. It is worth comparing the specific options within your size rather than picking by brand name alone, because the same size may differ in whitewall presentation, listed rim-width range, or load figure depending on the tire series.

For 1926 Stearns-Knight 700-21 tires, Firestone Balloon and Michelin Double Rivet differ in their listed details and available visual treatments. Firestone Balloon appears in Blackwall, Wide Whitewall, and Double-Whitewall versions, with a listed rim-width range of 3.75 to 4.00 inches and a maximum load figure of 1930 pounds at 40 psi on the Firestone entries. Michelin Double Rivet is listed as a Blackwall tire with a 3.00- to 3.75-inch rim-width range.

That means the Firestone range gives a 6S owner more sidewall-style variety and supports a slightly wider listed wheel range, while the Michelin entry may appeal to someone seeking a blackwall presentation on a narrower approved rim range. The right choice depends on the wheel already on the car and the final appearance you want. Compare the actual wheel width first, then choose the series whose visual style fits the character of your restoration.

Rim-width guidance is available for the listed 21-inch numeric sizes used on 1926 Stearns-Knight vehicles. In 600-21, BFGoodrich products are listed for 3.00- to 3.75-inch rim widths. In 700-21, Michelin Double Rivet is listed for 3.00- to 3.75-inch rims, while Firestone Balloon products are listed for 3.75- to 4.00-inch rims. Those ranges show that wheel width can vary even within the same 21-inch diameter family.

That matters because mounting a tire outside its approved width range can affect the tire’s shape, sidewall behavior, and final appearance on the car. Before selecting a tire, measure the actual wheel or confirm the wheel specification with a restorer familiar with your Stearns-Knight. Diameter alone is not enough. A 21-inch rim can still need a different tire choice depending on whether the wheel falls on the narrower or wider end of the approved range.

Original 1926 Stearns-Knight wheels can only be matched to the correct tire sizes once the model and wheel dimensions are confirmed. All listed product-bearing sizes use 21-inch rims, so there is shared rim diameter compatibility at that level. Even so, the 6C and 6S do not use the same tire widths, and the listed approved rim-width ranges differ between 600-21 and some 700-21 products.

In practice, that means a wheel that accepts one 21-inch size should not automatically be assumed correct for every other 21-inch Stearns-Knight tire. Start by identifying the car as a 6C or 6S, then confirm the wheel width before selecting among available tires. That step is especially important on older cars that may have seen wheel swaps, mixed spare assemblies, or past restorations that changed the size family without preserving the original marking convention.

A stored 1926 Stearns-Knight should be kept out of direct sunlight and away from ozone sources such as electric motors, compressors, battery chargers, and furnaces. The storage area should stay dry and reasonably stable in temperature, and the tires should be kept at the intended running pressure rather than left partially deflated. Because 1926 Stearns-Knight tires are bias-ply types, they are more prone to flat-spotting during long static periods than a modern radial.

Moving the car periodically helps change the contact patch and reduce temporary flat spots. For longer seasonal storage, many collectors either roll the car a short distance every few weeks or support the vehicle in a way that reduces continuous load on the tires while still keeping the suspension in a sensible condition. Clean, dark storage and simple movement habits do more for long-term tire condition than most specialty dressings or cosmetic treatments.

On a collector car like a 1926 Stearns-Knight, tire age matters more than mileage. Even if tread wear is minimal, most collector tires deserve close evaluation once they reach roughly five to seven years of age, and replacement becomes a serious consideration as they approach about ten years old. The manufacturing date can be confirmed from the tire’s date marking, and any signs of cracking, separation, or persistent air-loss should move the inspection timeline forward.

That age-based approach is especially important on a low-use luxury car that may spend long periods parked between outings. A tire can look presentable from a few feet away and still be aging internally. Keep a simple record of installation dates, inspect sidewalls in bright light, and do not let low annual mileage create a false sense of security. Time, storage conditions, and inflation history all influence service life on an antique vehicle.

Tires on a 1926 Stearns-Knight should be inspected before every drive and again before any longer tour or event. Look for sidewall cracking, tread damage, bulges, cuts, irregular wear, and signs that pressure has dropped since the last outing. A heavy luxury car from the 1920s places noticeable demand on its tires, so even small condition issues deserve attention before the car goes back on the road.

That inspection should include the spare, since an old or neglected spare is of limited use when you actually need it. If your car is running a tube-type setup, include the valve stem and any signs of tube-related leakage in your routine checks. A short walk-around before driving takes only a few minutes, but it is one of the most effective habits for keeping an antique Stearns-Knight ready for dependable local use.

A 1926 Stearns-Knight 6C would originally have used bias-ply tires, since radial construction was not a period production fitment for an American luxury car of this era. Within the 1926 Stearns-Knight range, the 6C is associated with the 33X6.00 and 600-21 size designations. That pairing reflects the balloon-tire period, when antique diameter-by-section and numeric conventions could both appear in reference to the same general era of fitment language.

For a restoration, the important part is matching the 6C to its proper size family and period-correct construction, then deciding how closely you want to follow original presentation details such as sidewall style. If your goal is concours-level accuracy, verify body style and market-specific expectations with a Stearns-Knight club or marque historian. They can help settle fine points that go beyond the broad year-and-model fitment picture.

Correct tire fitment absolutely matters when showing a 1926 Stearns-Knight. Judges and knowledgeable enthusiasts will notice whether the tire size family matches the model, whether the construction is era-appropriate bias-ply, and whether the sidewall treatment suits the car’s period character. A tire that is the wrong width family for a 6C or 6S, or a sidewall presentation that feels too modern for the restoration theme, can change the car’s stance and visual credibility immediately.

That does not mean every event applies the same standard, but tire details are often part of the first impression a car makes. If you are preparing for judged competition, review the event’s authenticity standards and compare them against your intended size and sidewall choice. Marque clubs and experienced show entrants are usually the best source for understanding whether a blackwall, whitewall, or more specialized period presentation best suits your exact Stearns-Knight.

For the 1926 Stearns-Knight 6C in 600-21, the listed BFGoodrich and Lester tires differ in specification detail and presentation options. BFGoodrich appears in both Blackwall and 3.50-inch Wide Whitewall versions, with a listed maximum load of 1350 pounds at 36 psi and an approved rim-width range of 3.00 to 3.75 inches. Lester is listed in Blackwall form in the same size, giving the 6C owner another period-style bias-ply option in a simpler visual treatment.

That comparison makes BFGoodrich the more visibly varied option in the listed 600-21 group, especially for a formal whitewall-oriented restoration. Lester may appeal to an owner pursuing a more understated blackwall look within the same size family. Since wheel width guidance is specifically listed on the BFGoodrich entries, confirm your wheel dimensions and compare the overall appearance you want before choosing between the available 6C offerings.

1926 Stearns-Knight tires can be suitable for normal road use when they are the correct size, in sound condition, and operated within the limits of their construction and the car itself. The listed sizes here are all bias-ply products, and no speed ratings are shown in the available product markings. On a 1920s luxury car, the vehicle’s own mechanical limits, including braking, steering feel, suspension design, and overall weight, are often a greater practical constraint than modern highway pace alone.

Safety on the road depends less on chasing a number and more on preparation. Fresh inspection, correct inflation, proper wheel fit, and realistic driving expectations matter far more than trying to treat a Stearns-Knight like a modern touring car. If the car will be driven beyond local roads, make sure the tires are age-appropriate, evenly worn, and holding pressure consistently, and keep the route and cruising speed in line with the capabilities of a 1926 automobile.

Inflation pressure for 1926 Stearns-Knight tires should start with the vehicle’s original factory recommendation for its model and size, then be checked against the tire manufacturer’s stated rated pressure for the specific reproduction tire you are using. Among the listed products, some 600-21 BFGoodrich tires show 1350 pounds at 36 psi, while some 700-21 Firestone tires show 1930 pounds at 40 psi. Those figures are tire-specific and should not be transferred from one size to another.

The safest approach is to use the correct size on the correct model and then tune inflation within the acceptable range for that tire and the car’s intended use. A heavier 6S on 700-21 tires should not be assumed to want the same pressure as a 6C on 600-21 tires. Keep all four tires consistent side to side, check pressure cold, and revisit it after long storage periods before putting the car back into service.

Before a longer drive in a 1926 Stearns-Knight, inspect every tire for cracking, cuts, bulges, uneven wear, embedded debris, and signs of aging around the sidewall and bead area. Confirm cold inflation pressure, look over the valve stems, and make sure the spare is usable and inflated. Because these cars use tall bias-ply tires, it is also wise to watch for any tire that has developed a noticeable flat spot after storage and to give it a short settling run before committing to a full day on the road.

The tire check should be part of a broader pre-drive review that includes brakes, steering, wheel-bearing condition, and the general readiness expected of a 1920s car. A Stearns-Knight may feel smooth and composed, but it still rewards conservative preparation. Catching a weathered sidewall, a soft spare, or a pressure mismatch in the garage is far easier than dealing with it on the shoulder during a tour or club event.