1948 Nash Tire Fitment Guide

1948 Nash vehicles use two different tire sizes depending on model. The Ambassador 60 uses 710-15 bias-ply tires, while the Ambassador 600 uses 640-15 bias-ply tires. Both sizes mount on 15-inch wheels, but they do not use the same rim-width range: 710-15 products fit 5.00 to 5.50-inch rims, while 640-15 products fit 4.00 to 5.00-inch rims depending on the specific tire.

That means the first step is identifying the model, not just the year and make. Once the model is confirmed, check the actual wheel width against the tire's approved range and then choose the sidewall style that matches your restoration goals. A 15-inch wheel alone is not enough to make the two sizes interchangeable.

On a 1948 Nash tire, 710-15 is a numeric bias-ply size. The 710 portion is the traditional nominal section-width designation used in period American sizing, and the 15 identifies the wheel diameter in inches. For 1948 Nash applications, that size belongs to the Ambassador 60 and is offered in bias-ply construction only.

Modern buyers sometimes expect a metric code with an aspect ratio and speed symbol, but a late-1940s American tire usually will not read that way. If your Nash is an Ambassador 60, staying with 710-15 preserves the original-style sizing language and keeps the car in the correct era of tire construction and appearance.

No. 1948 Nash models split between two sizes: the Ambassador 60 uses 710-15, and the Ambassador 600 uses 640-15. Both are 15-inch bias-ply tires, but the size itself changes by model, and the associated wheel-width ranges differ as well.

That distinction matters because many postwar cars from the same make can look broadly similar at a glance. If you are ordering for a project car, inherited car, or partially restored car, confirm the exact model designation before choosing a tire. It is the key detail that separates the correct fitment paths for 1948 Nash.

1948 Nash tires are available in several period-style sidewall treatments depending on size. The 710-15 size for the Ambassador 60 is offered in blackwall and wide whitewall versions. The 640-15 size for the Ambassador 600 includes wide whitewall choices as well as a narrow whitewall option.

Sidewall style affects the finished look of the car more than fitment, especially on a postwar Nash where the tire is part of the overall visual presentation. Buyers aiming for a formal late-1940s appearance often focus on whitewall width, while a more restrained look may point toward blackwall or a narrower stripe depending on the model and intended presentation standard.

BFGoodrich and Firestone both offer tires for 1948 Nash vehicles. Each brand appears in the 710-15 size used on the Ambassador 60 and in the 640-15 size used on the Ambassador 600. All listed options for these Nash fitments are bias-ply tires rather than radial conversions.

That gives buyers a choice between two long-established American names while still staying within the proper construction type for the period. The more meaningful comparison for most 1948 Nash owners is not brand alone, but which size belongs to the model and which sidewall treatment best matches the car's intended finish and use.

For 1948 Nash Ambassador 600 applications in 640-15, BFGoodrich and Firestone share the same basic bias-ply size and 15-inch rim diameter, but they differ in sidewall offerings and approved rim-width ranges. BFGoodrich is offered as a wide whitewall on 4.00 to 4.50-inch rims with a listed load of 1190 at 32 psi. Firestone appears in wide and narrow whitewall versions, generally fitting 4.50 to 5.00-inch rims, with most wide whitewalls listed at 1190 at 32 psi and one narrow whitewall listed at 970 at 32 psi.

Those differences matter when the wheel width is already known and when the car's appearance target is very specific. A buyer trying to match a certain whitewall look should compare the exact sidewall treatment first, then confirm the wheel width and load figure of the individual tire rather than assuming every 640-15 option is identical.

1948 Nash tire rim-width requirements depend on the size and model. The 710-15 tires used on the Ambassador 60 fit 5.00 to 5.50-inch rims. The 640-15 tires used on the Ambassador 600 fit narrower wheels, with approved ranges spanning 4.00 to 4.50 inches on some versions and 4.50 to 5.00 inches on others.

That is why wheel measurement matters even when the diameter is already known to be 15 inches. Before mounting a replacement tire, verify the actual rim width on the car and compare it with the specific tire you are considering. Staying within the listed range helps preserve the intended casing shape and fit.

Original 1948 Nash wheels can only be shared across tire sizes when both the wheel diameter and wheel width match the tire's requirements. Both 640-15 and 710-15 tires use 15-inch rims, so the diameter is common across the range. The limiting factor is width, since 710-15 needs a 5.00 to 5.50-inch rim and 640-15 products are approved on narrower widths depending on the tire.

In practical terms, that means a 15-inch wheel from one 1948 Nash model is not automatically suitable for the other model's tire size. If a car has had wheel changes during its life, measure before choosing tires. Shared diameter does not override the width requirement built into each size.

A stored 1948 Nash should be kept in a cool, dry, dark environment away from direct sunlight, electric motors, battery chargers, welders, and other ozone-producing equipment that can accelerate sidewall aging. Keep the tires properly inflated, move the car periodically if possible, and avoid letting it sit for long periods on damp concrete or in standing moisture.

Bias-ply tires are especially prone to developing temporary flat-spotting after long static storage, so a little movement helps. If the car will be parked for an extended stretch, some owners use stands to reduce load on the tires and suspension, but the key goal is steady conditions and protection from heat, ozone, and moisture.

Tires on a 1948 Nash should be evaluated by age as much as by tread wear, because collector cars often accumulate very little mileage. A sensible rule is to inspect closely once a tire reaches the five- to seven-year range and to treat around ten years as the point where replacement deserves serious consideration even if the tread still looks serviceable. The DOT date code on the tire helps establish age.

That approach is especially important on hobby cars that spend more time parked than driven. Old-looking tires are an obvious concern, but a low-mileage tire can still age out internally. If the date code shows significant age or the rubber is hardening and checking, replacement becomes a maintenance issue rather than a mileage issue.

Tires on a 1948 Nash should be checked before every drive and again before any longer outing. Look for sidewall cracking, cuts, bulges, uneven wear, tread separation signs, and pressure loss. Because these are bias-ply collector-car applications, it is also wise to pay close attention to valve stems and any tire that has been sitting in one position for an extended period.

A quick visual check is usually enough before a short local drive, but tour use deserves a more careful inspection. Collector cars can hide tire problems because they are driven infrequently, so regular inspection catches aging issues early. If a tire looks sound but the car feels newly harsh or wanders more than usual, inspect again before heading farther.

A 1948 Nash Ambassador 60 would have been fitted in bias-ply form, which was the standard American passenger-car construction in that period. For this model, the correct size path is 710-15 on a 15-inch wheel. Whitewall or blackwall appearance could vary by market, trim presentation, and owner preference, but the construction type and size family belong firmly in the bias-ply, numeric-size era.

Owners restoring for authenticity should begin with the 710-15 bias-ply size and then refine the sidewall treatment to match the car's intended presentation. If the goal is strict factory-style accuracy, a Nash club, period sales literature, or marque specialist can help verify whether a particular whitewall treatment suits the specific car and market.

Correct tire fitment matters on a 1948 Nash because judged restoration standards often consider size, construction type, and sidewall appearance as part of the car's overall authenticity. A 1948 Nash shown with the wrong model-specific size or with a sidewall style that clashes with the car's presentation can stand out to knowledgeable judges even when the rest of the restoration is strong.

For a formal show car, getting the model-specific size right is the foundation: 710-15 for the Ambassador 60 and 640-15 for the Ambassador 600. After that, attention usually shifts to whether the whitewall or blackwall treatment suits the period and the event's judging expectations. Marque clubs remain the best source for event-specific authenticity standards.

For the 1948 Nash Ambassador 60, BFGoodrich and Firestone 710-15 tires share the same basic fitment: bias-ply construction, 15-inch rim diameter, 5.00 to 5.50-inch rim-width range, and a listed load of 1550 at 32 psi. The visible difference is sidewall presentation, since BFGoodrich appears in both blackwall and wide whitewall versions, while Firestone is represented here in blackwall form.

That makes the choice largely one of appearance when the goal is an authentic-sized tire on the correct wheel. A restorer building a more restrained look may lean toward blackwall, while a car intended to reflect a dressier late-1940s style may call for a wide whitewall. Either way, the fitment foundation stays the same at 710-15.

1948 Nash tires in these applications are bias-ply collector-car tires, and no speed-rating markings are listed for the available 640-15 or 710-15 products. Safe highway use depends not only on the tire's condition and correct inflation, but also on the overall condition of the car, including brakes, steering, suspension, wheel bearings, and alignment. On a late-1940s Nash, those vehicle systems often set the practical comfort limit before outright tire capability becomes the main concern.

For real-world driving, the important question is whether the tires are fresh, properly fitted, and suited to the wheel, not whether the car can cruise at modern interstate speeds indefinitely. A well-sorted 1948 Nash can be enjoyed on public roads, but longer or faster trips deserve a careful mechanical check and realistic expectations consistent with the vehicle's era.

Available 1948 Nash tires in 710-15 and 640-15 sizes show load figures at 32 psi, but those numbers are tire ratings rather than a one-size-fits-all operating recommendation for every car and condition. The 710-15 tires are listed at 1550 at 32 psi, while most 640-15 versions are listed at 1190 at 32 psi and one narrow-whitewall 640-15 is listed at 970 at 32 psi.

Use the original Nash owner's information as the starting point for vehicle-specific pressure guidance, then compare it with the tire maker's stated rating for the exact tire you are using. Do not transfer a pressure from one size to another just because both fit 15-inch wheels. Size, load rating, and vehicle model all matter.

Before a longer drive in a 1948 Nash, inspect each tire for cracking, cuts, bulges, irregular wear, embedded debris, and stable air pressure. Check the spare as well, since a long-stored collector spare can age out quietly. Because these cars use model-specific tire sizes, confirm that all four road tires and the spare match the intended fitment for the model.

Tire condition is only one part of a longer-trip inspection on a postwar car. It is wise to combine the tire check with a broader review of brakes, cooling system, steering, charging system, and fluid levels before committing to distance. A careful pre-drive routine does more to protect the trip than any single tire choice alone.