1931 Graham Tire Fitment Guide

1931 Graham vehicles use four tire sizes across three models: 650-18 for the Graham Custom, 550-18 for the Graham Special and Graham Standard, 6.00-17 for the Graham Special, and 6.00-18 for the Graham Standard. All of them are bias-ply sizes. The 18-inch fitments include rim-width ranges of 3.25 to 3.50 inches for 650-18 and 3 to 4 inches for 550-18 on the currently available products.

That means year and make alone are not enough to choose a tire for a 1931 Graham. Start by identifying whether the car is a Custom, Special, or Standard, then confirm whether it wears 17-inch or 18-inch wheels before narrowing the choice by brand or sidewall style. On older restorations, wheel swaps are common enough that the actual rim diameter is worth checking by hand.

A 650-18 tire on a 1931 Graham is a traditional numeric bias-ply size. The 6.50 figure is the nominal section width, and the 18 is the rim diameter in inches. On this year and make, 650-18 is used on the Graham Custom, and the available tires are built for 18-inch wheels with a 3.25 to 3.50 inch rim-width range.

Numeric prewar tire sizing can look unfamiliar because it does not read like a modern metric radial code. For a 1931 Graham owner, the important takeaway is that 650-18 is not just a style variation of another size in the lineup; it is a distinct model-specific fitment tied to the Custom. If your car is a Custom, that code is the first thing to verify on the wheel and existing tire.

No, 1931 Graham models do not all use the same tire size. The Custom uses 650-18, the Special can use 550-18 or 6.00-17, and the Standard can use 550-18 or 6.00-18. Even where two models share 550-18, the lineup as a whole is not universal in either size or wheel diameter.

That variation matters because it affects more than appearance. A 17-inch fitment for a Graham Special is a different wheel requirement from any of the 18-inch choices, so selecting by year and make alone can send you in the wrong direction. If the car has been restored over many decades, compare the model identity, wheel diameter, and current tire markings before deciding which path is correct.

1931 Graham tires are available with several period-appropriate sidewall looks, depending on size. The 650-18 offerings include blackwall and wide whitewall versions, while 550-18 has the widest variety with blackwall, wide whitewall, and double-whitewall choices. All of the currently available options for this year and make are bias-ply tires, which keeps the visual profile in step with prewar construction.

Sidewall style often comes down to how the car will be presented. A blackwall usually suits a more restrained or utilitarian look, while whitewall treatments create a dressier appearance that many owners prefer on an upscale prewar sedan or touring car. If originality matters for a specific club or judging standard, compare your intended presentation with period photos and Graham marque resources before settling on one style.

Three brands cover the currently available 1931 Graham fitments: Firestone, Excelsior, and BFGoodrich. Firestone appears in both 650-18 and 550-18, while Excelsior and BFGoodrich are represented in 550-18. All of these offerings are bias-ply tires, which is appropriate for a 1931 American car and keeps the sizing and profile consistent with prewar expectations.

Brand choice on a 1931 Graham is usually less about changing the underlying fitment and more about selecting the look and presentation you want in the correct size. If you are choosing for a Custom, your available path is narrower because 650-18 is offered only in Firestone. Owners of Special and Standard models using 550-18 have more room to compare sidewall style and brand heritage within the same basic fitment.

On a 1931 Graham in 550-18, Firestone and BFGoodrich differ mainly in sidewall presentation, rim-width fitment, weight, and stated load figure. Firestone appears as a blackwall and as a 3.25 inch double whitewall, both on 3.25-inch rims with a listed maximum load of 1125 pounds at 32 psi. BFGoodrich is offered as a 3.00 inch whitewall on a 3-inch rim, with a listed maximum load of 1000 pounds at 32 psi.

That makes the decision less about one being universally better and more about matching the tire to the wheel and the look you want on the car. A Graham owner with narrower rims or a preference for a specific whitewall proportion may lean one way, while another owner may prefer the Firestone presentation or load specification. Check the actual wheel width before making that choice, especially on an older car that may no longer wear its original rims.

Rim-width requirements for 1931 Graham tires vary by size. The currently available 650-18 tires fit 18-inch rims that are 3.25 to 3.50 inches wide, and the available 550-18 tires fit 18-inch rims from 3 to 4 inches wide depending on brand and sidewall version. Those ranges are specific to the tire size and product, not a blanket rule for every 1931 Graham wheel.

Rim width matters because a tire that is right in diameter can still be a poor match if the wheel is too narrow or too wide for that particular casing. Before choosing among 550-18 options, measure the wheel or confirm its width through restoration records, especially if the car has changed hands several times. Staying within the stated rim-width range helps preserve proper shape, seating, and appearance.

A 1931 Graham owner should treat tube use as something to confirm product by product rather than assume from the size alone. The currently listed 650-18 and 550-18 product descriptions do not carry TT or TL markers in the size code, so the best approach is to verify the specific tire's sidewall marking and the wheel's design before finalizing the setup. That is especially important on prewar applications where original-style wheels often differ from later tubeless-era rims.

In practical terms, the wheel usually drives the decision as much as the tire does on a car from 1931. If the wheel is an original or original-type drop-center rim intended for tube service, plan your fitment research around that reality and inspect the valve-stem arrangement at the same time. Tube choice, flap requirements where applicable, and wheel condition should all be checked together rather than treated as separate decisions.

A 1931 Graham should be stored in a cool, dry, dark space away from direct sunlight, electric motors, welders, battery chargers, and other ozone-producing equipment that can age rubber. Bias-ply tires also tend to flat-spot more readily during long static storage than later radial designs, so tire pressure and vehicle position matter. Clean floors, stable temperatures, and protection from standing moisture all help preserve the casing and sidewalls.

For a collector car that sits for weeks or months, it helps to move the Graham periodically or place it on stands if the storage interval is long and the setup is appropriate for the vehicle. Avoid letting one spot on the tire carry the full load indefinitely. When the car comes back into service, give the tires time to round out and inspect the sidewalls closely before a meaningful drive.

Tire life on a 1931 Graham is usually judged more by age and condition than by mileage, because many prewar collector cars see limited annual use. A sensible rule is to evaluate tires closely once they reach the five-to-seven-year range and to treat around ten years as a point for serious replacement consideration, even if tread wear looks light. The DOT date code on the tire is the best reference for age.

That matters because an older bias-ply tire can look presentable at a glance while still hardening internally or showing early sidewall deterioration. If your Graham spends more time at shows than on the road, age can outpace wear by a wide margin. Keeping a written record of installation dates, storage conditions, and inspection findings is often more useful than relying on memory with a low-use antique car.

Tires on a 1931 Graham should be inspected before every drive, with a more thorough check before any longer outing. Look for sidewall cracking, cuts, bulges, irregular tread wear, and signs of pressure loss, and do not ignore the spare if it may be pressed into service. On a prewar car, valve stems, wheel condition, and bead area cleanliness deserve attention along with the tread and sidewall.

Frequent inspection is especially important because a collector car can sit long enough for age-related problems to develop between drives. Catching a crack, a slow leak, or a stem issue in the garage is far preferable to discovering it on the roadside in a heavy antique car. Make tire inspection part of the same routine as checking fluids, lights, and basic chassis condition before setting out.

A 1931 Graham Custom would originally have used bias-ply tires, because that was the standard construction for American passenger cars in this prewar period. Within the available fitments here, the Custom uses 650-18, which aligns with that era-correct construction approach and mounts on 18-inch rims. Original-equipment brand can vary by production period, selling dealer, and surviving records, so size and construction are the most reliable starting points.

For a faithful restoration, begin with the correct 650-18 size and then choose the sidewall treatment that best matches the way your particular car is being restored. A wide whitewall can create a more formal presentation, while a blackwall can suit a plainer period look. If you are restoring for judged authenticity, compare your car against factory literature, period photographs, and Graham club references before making the final call.

Correct tire fitment absolutely matters when showing a 1931 Graham, especially in venues that value historical accuracy. Judges and experienced marque enthusiasts commonly notice whether the size is right for the model, whether the construction matches the era, and whether the sidewall style looks appropriate to the car's period presentation. A visibly incorrect wheel diameter or a tire style that clashes with early-1930s practice can distract from an otherwise strong restoration.

That does not mean every event uses the same standard, but it does mean tire choice should be part of the restoration plan rather than an afterthought. If your goal is club-level or concours judging, verify the model-specific size first, then make sure the sidewall appearance suits how the car would have been presented in its day. Event-specific rules are best confirmed with the hosting club or Graham marque community.

For a 1931 Graham using 550-18 tires, Firestone and Excelsior differ in fitment details and presentation. The listed Excelsior Comp H is a blackwall bias-ply tire for a 4-inch rim, while the Firestone 550-18 offerings include blackwall and double-whitewall bias-ply versions for 3.25-inch rims, with listed maximum loads of 1125 pounds at 32 psi on the Firestone products that carry load data. Weight also differs, with the Excelsior at 18 pounds and the Firestone versions heavier.

For a restoration-minded owner, those differences can influence both appearance and wheel compatibility. A car wearing 4-inch rims points toward a different setup than one built around 3.25-inch rims, even though both use the same nominal tire size. If you are trying to match an established restoration or period look, compare rim width, sidewall styling, and overall visual stance before choosing between the two brands.

A properly selected and properly maintained tire can be suitable for normal road use on a 1931 Graham, but highway confidence depends on the tire's condition, the wheel setup, and the car's broader mechanical health as much as the size itself. The currently listed 650-18 and 550-18 products do not show speed-rating letters in their size descriptions, so the focus should stay on using the correct bias-ply fitment in sound condition and keeping the car within sensible operating limits for a prewar automobile.

A 1931 Graham's braking, suspension, steering, and road manners were engineered in a very different era, so tire selection is only one part of the equation. Before sustained higher-speed use, make sure the tires are the correct model-specific size, properly inflated, and free from age damage. Then consider the entire vehicle honestly, because the safest pace for an antique car is often determined more by the car than by the tire.

Inflation pressure for a 1931 Graham should follow the vehicle manufacturer's original guidance where available, while also respecting the tire maker's own rated pressure information for the specific reproduction tire you choose. Among the listed products, some 550-18 tires carry maximum load figures at 32 psi, including 1125 pounds at 32 psi and 1000 pounds at 32 psi, while one 650-18 tire lists 1205 pounds at 36 psi. Those figures are load-and-pressure ratings, not a universal cold-pressure setting for every Graham.

The practical approach is to match the exact tire size and product first, then compare its published limits with the pressure guidance appropriate to your car's use. Do not transfer a pressure figure from 550-18 to 650-18 or assume all versions of one size should run the same. On an antique vehicle, a few pounds can noticeably affect ride, steering feel, and tread shape, so accuracy matters.

Before a longer drive in a 1931 Graham, inspect each tire for cracking, cuts, bulges, uneven wear, and proper inflation, and include the spare in that check. Look over valve stems, make sure the beads are seated properly, and confirm that the tire size on the car actually matches the model and wheel diameter you intend to run. Because these are prewar bias-ply applications, any sign of age hardening or casing distortion deserves attention before departure.

Tires are only one part of preparing an antique car for distance, but they are one of the easiest places to prevent trouble. Once the tire inspection is complete, fold it into a broader pre-drive review of brakes, steering, wheel fasteners, fluids, and lights. On a 1931 Graham, that kind of old-car discipline does more for a successful trip than relying on tread depth alone.