The 1931 Graham Standard comes from an era when independent automakers competed on style, value, and mechanical distinction during the heart of the prewar American market. For owners restoring or maintaining one today, tire choice is closely tied to the car’s original road-going character and its exact engine designation. The 1931 Graham Standard uses bias-ply tires on 18-inch rims, with 550-18 tied to the 6 Cyl. model and 6.00-18 used on the 8 Cyl. model. Within the covered options, the 550-18 size opens the door to blackwall, wide whitewall, and double-whitewall presentations across several traditional series. The key is matching the correct size to the correct sub-model, then choosing the appearance and specification that suit the car’s restoration goals and driving use.
Which Tire Size Is Right for The 1931 Graham Standard
Two tire sizes apply to the 1931 Graham Standard, and the right one depends on identifying the exact sub-model first. Both are bias-ply sizes built for 18-inch rims, but the 6 Cyl. and 8 Cyl. versions do not use the same tire. Once the sub-model is confirmed, the decision shifts to traditional blackwall or whitewall styling, brand preference, and matching the tire to the wheel already on the car.
A 550-18 size uses the older numeric bias-ply system, where the 5.50 designation refers to the tire’s nominal section width in inches and 18 identifies the rim diameter. On the 1931 Graham Standard, this is a bias-ply fitment for the 6 Cyl. sub-model and keeps the car in a distinctly prewar sizing format. Available choices include Excelsior, Firestone, BFGoodrich, and Michelin, with blackwall, wide whitewall, and double-whitewall styling represented across several series. It is the size to evaluate when the goal is preserving traditional proportions while still choosing the sidewall treatment and rim-width specification that match the wheel on the car.
A 6.00-18 tire follows the same numeric bias-ply naming convention, with 6.00 indicating a nominal six-inch section width and 18 denoting the wheel diameter. For the 1931 Graham Standard, this size belongs to the 8 Cyl. sub-model and represents a wider prewar bias-ply fitment than 550-18. Its practical importance is not just the number on the sidewall, but the fact that it separates the 8 Cyl. car from the smaller 6 Cyl. application. This is the size to confirm carefully before purchase, especially if the car has changed hands, been restored previously, or no longer wears its original wheel setup.
Sub-model fitment matters on the 1931 Graham Standard because the covered 6 Cyl. and 8 Cyl. versions do not share the same tire size. Both use bias-ply tires on 18-inch rims, but selecting the correct size starts with confirming which engine-designated model is actually in front of you.
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1931 Graham Standard 6 Cyl.
The 1931 Graham Standard 6 Cyl. uses the 550-18 bias-ply size on an 18-inch rim. That makes tire selection more about choosing the right period-style brand and sidewall treatment within that size than comparing multiple primary fitments.
The 1931 Graham Standard 8 Cyl. uses the 6.00-18 bias-ply size on an 18-inch rim. The main task here is confirming that the car still carries the wheel and fitment setup appropriate to the 8 Cyl. model before selecting a replacement tire.
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Best 1931 Graham Standard Tires for Sale
Available 550-18 tires span Excelsior, Firestone, BFGoodrich, and Michelin, with choices that include blackwall, wide whitewall, and double-whitewall presentations. Product differences also extend across traditional series and rim-width specifications, which gives restoration-minded buyers more than one way to match the car’s intended look.
Owners of a 1931 Graham Standard usually need to sort out the correct sub-model tire size first, then compare prewar bias-ply options by rim fitment, sidewall style, and restoration goals. The questions below focus on those decisions, along with inspection and road-use checks for a collector-era car.
Tire Size & Fitment
What tire size fits a 1931 Graham Standard?
A 1931 Graham Standard uses either 550-18 or 6.00-18, depending on the sub-model. The 6 Cyl. version uses 550-18, while the 8 Cyl. version uses 6.00-18. Both are bias-ply tire sizes built for 18-inch rims and follow the older numeric sizing system common on prewar American cars.
The most important step is confirming whether the car is a 6 Cyl. or 8 Cyl. model before choosing a tire. Many surviving cars have been restored, stored for long periods, or changed over the years, so it also helps to verify the wheel already on the vehicle rather than relying only on a previous owner’s notes.
What size rim does a 1931 Graham Standard use?
The 1931 Graham Standard uses an 18-inch rim with both covered tire sizes. That remains true whether the car is equipped with the 550-18 tire used on the 6 Cyl. model or the 6.00-18 tire used on the 8 Cyl. model. The key difference between the two fitments is tire size, not wheel diameter.
Rim diameter alone does not settle the fitment question, because both sub-models share the same 18-inch wheel diameter. The buyer still needs to confirm the exact sub-model and compare the wheel’s width with the tire being considered, especially if the car has replacement rims or older restoration parts that may not match the original setup.
Why does the 1931 Graham Standard have more than one tire size?
The 1931 Graham Standard has more than one tire size because the covered sub-models do not use the same fitment. The 6 Cyl. model takes 550-18, while the 8 Cyl. model takes 6.00-18. Both are prewar numeric bias-ply sizes on 18-inch rims, but they are not the same width designation.
That distinction matters because a buyer cannot treat the 1931 Graham Standard as a one-size-fits-all application. Tire selection needs to start with the specific sub-model, then move to wheel confirmation and appearance choices such as blackwall or whitewall. On a collector car, it is also smart to check what is actually mounted today before replacing anything.
Choosing the Right Tire
What should I consider when choosing a 550-18 tire for a 1931 Graham Standard?
For a 1931 Graham Standard that uses 550-18, start by confirming that the car is the 6 Cyl. sub-model and that the wheel is still an 18-inch setup appropriate to that tire. From there, the main choices are brand, traditional bias-ply construction, sidewall presentation, and the rim-width specification tied to the individual tire.
The available 550-18 products vary in character even though they share the same basic size. Blackwall options suit a more understated prewar look, while wide whitewall and double-whitewall versions create a stronger restoration-style presence. Comparing series names, wheel compatibility, and details such as load figures where shown can help narrow the right tire for the car’s intended use.
What sidewall styles are available for 1931 Graham Standard tires?
In 550-18, the 1931 Graham Standard is offered with several sidewall styles, including blackwall, wide whitewall, and double-whitewall. Those choices all stay within a traditional bias-ply presentation, but they create noticeably different visual results on a prewar car. The sidewall is often one of the biggest appearance decisions in a restoration-oriented tire purchase.
A blackwall tire keeps the look restrained and mechanical, while a wide whitewall or double-whitewall adds more visual emphasis around the wheel opening. The right choice depends on how the car is being presented rather than on one style being universally correct. Buyers focused on historical accuracy should compare the tire appearance with period photos or marque-specific references.
What brands offer tires for the 1931 Graham Standard?
For the 550-18 fitment used on the 1931 Graham Standard 6 Cyl., available brands include Excelsior, Firestone, BFGoodrich, and Michelin. Those options span several traditional series, including Comp H, Firestone Classic Bias Ply, Silvertown Classic Bias Ply, and Double Rivet. Each keeps the buyer within a prewar-style bias-ply category rather than shifting into a modern radial format.
Brand selection is best treated as part of the overall presentation and specification decision, not as a shortcut to fitment. The tire still needs to match the car’s sub-model, 18-inch wheel, and intended look. It also helps to compare sidewall style and wheel-width suitability alongside the brand name, since those details can matter just as much on an older restoration.
Restoration & Appearance
Which tire should I choose for a period-style 1931 Graham Standard?
A period-style 1931 Graham Standard should begin with the correct primary bias-ply size for the specific sub-model: 550-18 for the 6 Cyl. or 6.00-18 for the 8 Cyl. Staying with the proper prewar numeric size preserves the proportions and visual character that belong on a car from this era. Construction matters just as much as the sidewall appearance.
After the size is settled, the decision usually becomes blackwall versus whitewall styling and which traditional series best suits the restoration. A brighter whitewall treatment can change the car’s entire visual presence, while blackwall keeps it more restrained. When exact originality matters, compare the chosen look against marque-club guidance, period photography, or other vehicle-specific historical references.
Does correct tire fitment matter for a 1931 Graham Standard restoration?
Correct tire fitment matters a great deal on a 1931 Graham Standard restoration because the tire contributes heavily to both stance and authenticity of presentation. Using the right size for the right sub-model helps preserve the car’s proportions, while the correct prewar bias-ply construction supports the look and feel expected from a vehicle of this period.
A tire that is merely close in size can still alter the finished appearance or create questions about the wheel setup on a judged or carefully researched restoration. Sidewall treatment matters too, but it should come after the size and wheel are confirmed. Careful buyers usually verify the sub-model, existing rim, and restoration goal before deciding on the final tire style.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1931 Graham Standard?
Modifications can affect tire fitment on a 1931 Graham Standard, even when the tire size itself is correct for the sub-model. Replacement wheels, changed wheel widths, suspension work, altered ride height, or body repairs around the fenders can all influence how a bias-ply tire sits and clears. That matters on both the 550-18 and 6.00-18 applications.
Any car that has been restored over many decades deserves a fresh wheel-and-clearance check before new tires go on. Measuring the installed rim, checking steering movement, and inspecting space at the fender and suspension points can prevent expensive mistakes. Prewar cars often carry a long service history, so visible verification is more valuable than assumptions based on age alone.
What should I inspect before driving a 1931 Graham Standard on new tires?
Before driving a 1931 Graham Standard on new tires, inspect the wheels for condition, confirm the wheel diameter and width, and make sure the tires match the correct sub-model size. The rest of the check should include valve stems, inflation, even seating on the rim, and basic clearance during steering movement and suspension travel.
A collector-era car also deserves a broader road-readiness inspection before regular use. Brake condition, steering play, worn suspension parts, and wheel fastener security all influence how the car will feel once fresh bias-ply tires are installed. A short local test drive is a smart first step, especially after long storage or a restoration that has only recently been completed.
How should 1931 Graham Standard tires be maintained on a collector car?
Tires on a collector 1931 Graham Standard should be maintained with regular pressure checks, visual inspections, and careful storage habits. Bias-ply tires on older cars benefit from routine checks for cracking, cuts, bulges, flat spotting, uneven wear, and slow air loss. A low-mileage collector car can still have tire issues even when the tread looks usable.
Storage conditions matter almost as much as mileage. Keeping the car away from prolonged sunlight, excessive heat, moisture, and ozone sources can help preserve the tire over time. It is also wise to inspect the tires before each driving season and before any longer outing, since long periods of inactivity often reveal age-related issues that do not show up on regularly driven vehicles.
