1927 Moon Tire Fitment Guide

1927 Moon vehicles use six sizes across three model lines, and each model has its own pair of fitments. The 1927 Moon 60 Royal uses 29X5.25 and 5.25-19, the 1927 Moon 60 Series uses 29X4.75 and 4.75-20, and the 1927 Moon A uses 30X5.25 and 5.25-20. The 60 Royal sizes mount on 19-inch wheels, while the 60 Series and A sizes mount on 20-inch wheels.

That means year and make alone are not enough to choose a tire for a 1927 Moon. Start by identifying the model, then confirm whether you are matching an antique diameter-by-section marking or a numeric bias-ply equivalent. If the car has already been restored, compare the tire size on the sidewall and the actual wheel diameter before choosing a replacement.

On a 1927 Moon tire, 29X5.25 is an antique size format. The 29 refers to the tire’s overall diameter in inches, while 5.25 refers to nominal section width. On the 1927 Moon range, that size applies to the 60 Royal and is built as a bias-ply tire for a 19-inch wheel application.

Antique sizing can look unfamiliar if you are used to modern metric or later alphanumeric tires, but it was normal for the period. On a restoration, that format often matters because the sidewall marking contributes to the visual character of the car. If your 1927 Moon 60 Royal already wears a numeric size, compare both the sidewall marking and wheel diameter before deciding which convention you want to stay with.

On a 1927 Moon tire, 5.25-19 is a numeric bias-ply size. The 5.25 is the nominal section width in inches, and the 19 is the rim diameter in inches. Within the 1927 Moon lineup, this size belongs to the 60 Royal and serves as the model’s numeric counterpart to the older 29X5.25 style of marking.

Numeric bias-ply sizes are often easier for modern buyers to interpret because the wheel diameter is stated directly. Even so, they are still period-appropriate bias-ply fitments rather than modern radial conversions. If your goal is accurate fitment on a 1927 Moon 60 Royal, use the model identification and actual wheel diameter as your first checks, then decide which sidewall size convention best suits the car.

For a 1927 Moon, the antique and numeric sizes shown for each model are both bias-ply fitments, so the decision is more about size convention and restoration presentation than switching between bias-ply and radial construction. The 60 Royal pairs 29X5.25 with 5.25-19, the 60 Series pairs 29X4.75 with 4.75-20, and the A pairs 30X5.25 with 5.25-20. Each pair belongs only to its respective model.

Owners who want an earlier late-1920s look often prefer the antique diameter-by-section marking, while others prefer the direct wheel-diameter clarity of the numeric equivalent. Neither choice should be made by year and make alone, because the three Moon models do not share a common size. Check the model first, then compare the tire already on the car and the wheel diameter before settling on the replacement style.

The 1927 Moon lineup was not built around one universal tire size, and that was common in the late 1920s as wheel diameters and tire dimensions varied across body and series designations. The 60 Royal uses 19-inch fitments, while both the 60 Series and A use 20-inch fitments. The A also carries a wider 5.25-inch section size than the 60 Series, which uses 4.75-inch sizing.

That variation matters because two cars from the same make and year can require different tires even when their styling looks broadly similar. A buyer researching a 1927 Moon should confirm the exact model name from title records, firewall tags, club references, or existing restoration notes before moving to tire selection. That extra step prevents ordering a 20-inch fitment for a 19-inch 60 Royal or mixing the A and 60 Series sizes.

A restored 1927 Moon should be matched by checking three things together: the model designation, the wheel diameter actually on the car, and the size marking already fitted if the restoration has been stable and correct. The 60 Royal belongs with 29X5.25 or 5.25-19, the 60 Series with 29X4.75 or 4.75-20, and the A with 30X5.25 or 5.25-20. All of these are bias-ply period fitments rather than modern metric replacements.

Restored cars sometimes carry substitutions made decades earlier, so a sidewall alone should not be the only guide. Measure the wheel diameter at the bead seat and compare it with the model’s expected fitment before replacing anything. If the car is intended for judged use, compare the sidewall size convention to period references and marque-club guidance so the tire looks right as well as fits correctly.

1927 Moon vehicles use late-1920s bias-ply tire sizes that were originally part of an inner-tube era. For fitment on a collector car of this age, tube use is commonly part of the overall wheel-and-tire setup, especially when original-style wheels are retained. The exact tube requirement should always be matched to the specific tire construction and the wheel being used.

That makes it important to verify the intended setup before finalizing the tire choice, especially on a car that still wears original or original-style rims. Tube, flap, and valve-stem compatibility can be just as important as the sidewall size on a 1927 Moon. If the car has unusual restored wheels or mixed-era components, consult a Moon specialist or experienced pre-war tire installer before mounting.

Original 1927 Moon wheels cannot be treated as universal across the entire model range because the cars did not all use the same rim diameter. The 1927 Moon 60 Royal uses 19-inch fitments, while the 1927 Moon 60 Series and 1927 Moon A use 20-inch fitments. That difference alone prevents one original wheel setup from serving every 1927 Moon model without change.

Within a single model, the antique and numeric size pair may correspond to the same basic wheel diameter, but that still needs to be confirmed against the actual wheels on the car. Restorations can pick up swapped wheels over time, especially on low-production independents. Before replacing tires, inspect the wheel diameter directly and make sure the tire size you choose belongs to the same model family as the car.

A 1927 Moon should be stored in a cool, dry, dark space away from direct sunlight, electric motors, battery chargers, furnaces, and other ozone-producing equipment that can accelerate sidewall aging. Bias-ply tires also tend to flat-spot more readily than modern radials when a collector car sits for long periods. Clean floors, stable temperatures, and protection from moisture all help preserve both the tire and the wheel.

If the 1927 Moon will sit for weeks or months, move it periodically or place it on stands in a way that supports the car safely and reduces prolonged load on one contact patch. Keep inflation checked even during storage, because underinflation while parked can distort an older tire casing. A storage plan matters just as much as mileage on a low-use pre-war car.

Tires on a 1927 Moon should be judged more by age, storage history, and condition than by miles driven. On collector vehicles, a useful rule is to evaluate tires closely once they reach about five to seven years of age and to treat roughly ten years as a point where replacement deserves serious consideration even if tread remains. The DOT date code, when present on modern reproduction tires, is the starting point for that timeline.

A low-mileage pre-war car can still be riding on tires that look acceptable from a distance but are aging internally. Sidewall cracking, tread separation signs, hardening rubber, and persistent flat-spotting all matter more than odometer readings. If the service age is unclear on a 1927 Moon, an inspection by a knowledgeable vintage-tire specialist is a wise step before regular driving.

Tires on a 1927 Moon should be inspected before every drive and again before any extended outing. Look closely for sidewall cracking, cuts, bulges, irregular tread wear, embedded debris, and pressure loss. On an older tube-era setup, the valve stems and the condition of the spare deserve the same attention as the four road tires.

Frequent inspection is especially important on a collector car that may sit for long intervals between uses. Problems often appear from age, storage conditions, or wheel-related issues rather than heavy road mileage. A quick walkaround before every drive and a more deliberate inspection at the start of each season helps catch issues early and protects the rest of the restoration as well.

A 1927 Moon 60 Royal would originally have been a bias-ply application, which was the standard passenger-car construction for the period. Within the 1927 Moon range, the 60 Royal is associated with 29X5.25 and 5.25-19, both tied to its 19-inch wheel fitment. Those size conventions reflect the late-1920s transition between antique-style diameter-by-section labeling and numeric bias-ply replacement language.

For a restoration, that means the first authenticity questions are size convention, wheel diameter, and sidewall appearance rather than searching for a modern substitute format. If the car is being prepared for judged events, verify whether the event favors the antique marking, the numeric equivalent, or a market-specific interpretation. Moon club members and pre-war judging references are the best sources for final trim- and venue-specific confirmation.

Correct tire fitment matters on a 1927 Moon because judges and knowledgeable enthusiasts often notice whether the size, construction type, and sidewall style match the era and the specific model. A 60 Royal on a 20-inch size, a 60 Series on an A-model width, or any obvious move away from period bias-ply construction can stand out on a car presented as authentically restored. Tire markings themselves also contribute to the historical look.

That does not mean every event uses the same standard, but it does mean tire choice is part of the restoration story rather than an afterthought. If originality is the goal, confirm the model first, then make sure the chosen size belongs to that specific 1927 Moon line. Event organizers, marque clubs, and experienced pre-war restorers can clarify how strictly construction and sidewall appearance are judged.

A 1927 Moon restoration may show both antique and numeric tire sizes because late-1920s fitment history is often expressed in two related naming systems. Antique sizes such as 29X5.25 and 30X5.25 describe overall tire diameter and section width, while numeric sizes such as 5.25-19 and 5.25-20 state section width and wheel diameter more directly. Both belong to the period, and each Moon model pairs with its own matching set.

That dual-language sizing can confuse buyers who assume one of the markings must be modern, but both are still bias-ply, era-appropriate references. The better choice depends on how the car is being presented and what the current restoration already uses. If consistency and authenticity matter, keep the sidewall convention aligned across all five tires rather than mixing antique and numeric markings casually.

A properly fitted, correctly inflated, and sound-condition tire can make a 1927 Moon usable on modern roads, but road safety depends on the entire car as much as the tires. All of the fitments associated with the 1927 Moon range are bias-ply designs, so steering feel, tracking, braking response, and straight-line behavior will reflect pre-war tire construction. On a car of this age, mechanical condition often becomes the more important limitation before the tire itself does.

That means highway use should be approached with realistic expectations rather than modern-car assumptions. Verify age and condition, inspect for cracking or casing problems, and make sure the suspension, steering, and brakes are equally ready for sustained driving. A 1927 Moon in excellent tune can be enjoyed on public roads, but it rewards conservative speeds and careful preparation.

Inflation pressure for 1927 Moon tires should be set by the correct specification for the exact tire size and the vehicle’s original operating guidance, not by copying a number from a different Moon model or a different size. The 60 Royal, 60 Series, and A all use different fitments, so pressure should stay tied to the specific size and application. Reproduction tire recommendations and the car’s original literature should be read together rather than treated as interchangeable.

Pressure has a major effect on ride quality, steering effort, tread wear, and casing life on a bias-ply collector tire. Even a small mismatch can make a pre-war car feel unsettled or can accelerate shoulder wear. Once the correct size has been confirmed for the 1927 Moon model, use the applicable guidance for that exact tire and recheck cold pressure regularly rather than setting it once and forgetting it.

Before a longer drive in a 1927 Moon, inspect each tire for sidewall cracking, cuts, bulges, exposed cords, irregular wear, and secure valve stems, then confirm cold pressures and the condition of the spare. Because these are late-1920s bias-ply fitments, it is also wise to watch for signs of long-sit flat-spotting or any shake that suggests a mounting, tube, or wheel issue. Tire readiness should be part of a broader pre-drive inspection of the entire car.

A longer outing in a pre-war automobile asks more of every system than a short local drive. Along with the tires, check wheel fasteners, brakes, steering play, fluid levels, and the basic roadside tools you would want if a stop becomes necessary. On a 1927 Moon, confidence on the road usually comes from thorough preparation rather than from any single component.