1973 GMC Tire Fitment Guide

1973 GMC vehicles use a wide range of sizes rather than one universal fitment. C/K Pickup spans 700-15, G78-15, L78-15, H78-15, 700-16, LR78-15, 875-16.5, 950-16.5, 750-16, 800-16.5, and 10-16.5. Jimmy uses E78-15, F78-15, 700-15, G78-15, H78-15, and L78-15. Rally uses F78-14, G78-14, G78-15, H78-15, 800-16.5, and 875-16.5. Sprint uses G70-14, G78-14, GR70-14, and H78-14. Suburban uses 700-15, G78-15, H78-15, L78-15, LR78-15, 700-16, 750-16, 875-16.5, and 950-16.5. Vandura uses 700-14, E78-14, F78-14, 670-15, G78-15, H78-15, HR78-15, 800-16.5, 875-16.5, and 950-16.5.

Rim diameter is the first thing to verify because 1973 GMC applications cover 14-, 15-, 16-, and 16.5-inch wheels. Rim-width guidance is available for many of these sizes, including 700-15 at 5.00 to 5.50 inches, G78-15 at 5.00 to 7.00, L78-15 at 5.50 to 8.00, H78-15 at 5.50 to 7.00, 700-16 at 4.50 to 5.50, 750-16 at 5.00 to 6.00, 950-16.5 at 6.50 to 6.75, 800-16.5 at 6.00 to 6.50, 10-16.5 at 8.25, G78-14 at 5.00 to 7.00, G70-14 at 6.0 to 8.0 or 6.50 to 7.00 depending on brand, and 670-15 at 4.50 to 6.00 depending on tire.

G78-15 is an alphanumeric bias-ply size used on several 1973 GMC applications, including C/K Pickup, Jimmy, Rally, Suburban, and Vandura. In that older sizing system, the letter-and-number combination identifies the tire's relative section and load class, while the 15 refers to a 15-inch wheel diameter. Because there is no R in the code, it is a bias-ply size rather than a radial one. Available versions include wide whitewall passenger-style tires and blackwall truck-style tires.

That code matters because G78-15 does not mean the same thing as a numeric 700-15 or a radial LR78-15, even though all three fit 15-inch wheels. A buyer choosing for a 1973 GMC should compare the exact size stamped on the existing tire or called for by the vehicle's original literature, then confirm that the wheel width falls within the tire's approved range. On a truck or van that can use more than one 15-inch size, the sidewall style and overall stance may change along with the size code.

700-15 is a numeric bias-ply size used on 1973 GMC C/K Pickup, Jimmy, and Suburban applications. In this older inch-based format, the leading number represents nominal section width class and the 15 is the wheel diameter in inches. The code does not include an R, so it is not a radial designation. On 1973 GMC applications, 700-15 appears in both classic passenger-style whitewalls and more utilitarian blackwall versions.

Numeric sizes can be confusing because they coexist with alphanumeric sizes on the same year and make. A 1973 GMC owner should not assume that any 15-inch tire is interchangeable just because the rim diameter matches. The better approach is to confirm the exact size family first, then compare wheel width and intended use. That matters especially on pickups and Suburbans, where 15-inch fitments also include G78-15, H78-15, L78-15, and a radial-format LR78-15 in certain applications.

LR78-15 is an alphanumeric radial size used on 1973 GMC C/K Pickup and Suburban applications. The R in the code is the key detail because it identifies radial construction, while the 15 refers to a 15-inch wheel diameter. Firestone offers this size as a narrow whitewall radial with a published 1970-pound maximum load at 32 psi. It differs from G78-15, H78-15, and L78-15, which are bias-ply formats even though they share the same rim diameter.

For a 1973 GMC owner, LR78-15 is less about wheel diameter than about construction choice and driving character. It keeps a period-correct size language while moving to radial construction, which many owners prefer for regular road use. Even so, the tire still needs to match the wheel width, which runs 5.50 to 8.00 inches on the available LR78-15 product. Confirming that range against the actual wheel is the smart final step before choosing it over a traditional bias-ply 15-inch size.

No, 1973 GMC models do not use the same tire size. The C/K Pickup alone spans 11 sizes, while Jimmy uses six, Rally uses six, Sprint uses four, Suburban uses nine, and Vandura uses 10. Some sizes overlap across multiple models, such as G78-15 and H78-15, but many fitments are model-specific. Examples include 10-16.5 for C/K Pickup, GR70-14 for Sprint, and 670-15 or HR78-15 for Vandura.

That variation means year and make are only the starting point on a 1973 GMC search. A buyer who stops at 1973 GMC without identifying the model can easily land on the wrong rim diameter or the wrong size family. The practical move is to identify the exact model first, then verify the wheel diameter already on the vehicle, then compare the size code and construction style. That sequence is especially important when trucks, vans, and car-based GMC models are all grouped under the same year and make.

On 1973 GMC applications that use LR78-15, the real comparison is radial versus bias-ply rather than simply one 15-inch tire versus another. LR78-15 is a radial-format tire used on C/K Pickup and Suburban, while 700-15, G78-15, H78-15, and L78-15 are bias-ply formats used on various 15-inch truck and utility applications. The radial option keeps a vintage size code but changes the construction type. That usually makes it the modern-driving-minded alternative within the period-correct appearance spectrum.

Owners building a factory-style restoration often stay with the original bias-ply family that matches the vehicle's era and visual character. Owners who plan more regular road use may prefer LR78-15 where it applies because it preserves a classic look while moving to radial construction. The decision still has to be filtered through the exact model and wheel width, since not every 1973 GMC uses the same 15-inch tire and LR78-15 applies only to certain C/K Pickup and Suburban setups.

1973 GMC tires span a remarkably broad sidewall range. Whitewall offerings include wide whitewall and narrow whitewall styles across sizes such as 700-15, L78-15, 700-16, 750-16, G78-14, H78-14, F78-14, E78-14, and 670-15. Blackwall choices appear throughout the truck and van sizes, including 700-15, G78-15, H78-15, 700-16, 875-16.5, 950-16.5, 800-16.5, 700-14, E78-14, and 670-15. Sprint fitments also reach into more overtly sporty sidewalls such as redline, RWL, pin white stripe, and dual-white-stripe treatments.

The right sidewall style usually follows the personality of the specific 1973 GMC model. A Sprint often looks most at home with period performance sidewalls, while a Vandura, Rally, Jimmy, or Suburban may lean either toward whitewall passenger style or plain blackwall utility depending on how it is being restored. For show use, sidewall style can matter nearly as much as size and construction. For casual driving, it often comes down to the look you want against the wheel and body style.

Several brands cover the 1973 GMC range, though not every brand appears in every size. Firestone shows up in sizes such as 700-15, 700-16, 750-16, G70-14, and LR78-15. BFGoodrich appears in 700-15, L78-15, 700-16, 750-16, G78-14, and 700-14. Coker Classic covers many alpha-size passenger applications such as G78-15, L78-15, H78-15, F78-14, G78-14, H78-14, and E78-14. STA dominates many truck-oriented blackwall sizes, while Lester, Avon, Goodyear, US Royal, and Universal Vintage Tire also appear in specific applications.

Brand choice on a 1973 GMC often follows the type of vehicle and the look you want rather than year and make alone. A Sprint buyer may focus on Firestone or Goodyear performance-style sidewalls, while a heavy-duty pickup or van owner may end up in STA truck lines on 16.5-inch wheels. Whitewall restorations open the door to several brands in selected sizes. The best way to narrow the field is to settle the exact size first, then compare the brands that actually build that particular fitment.

Rim width depends entirely on the size used on the 1973 GMC model in question. Examples include 700-15 at 5.00 to 5.50 inches, G78-15 at 5.00 to 7.00, H78-15 at 5.50 to 7.00, L78-15 at 5.50 to 8.00, LR78-15 at 5.50 to 8.00, 700-16 at 4.50 to 5.50, 750-16 at 5.00 to 6.00, 950-16.5 at 6.50 to 6.75, 800-16.5 at 6.00 to 6.50, and 10-16.5 at 8.25. On the 14-inch side, G78-14 runs 5.00 to 7.00, G70-14 runs from 6.0 to 8.0 or 6.50 to 7.00 depending on brand, and 700-14 runs 5.00 to 5.50.

Those ranges are important because even when two tires share the same rim diameter, they may not belong on the same wheel width. A 15-inch wheel that works with 700-15 may not be the ideal match for LR78-15 or L78-15 without checking the actual width. Before ordering for a 1973 GMC, measure the wheel if there is any doubt, especially on vehicles that may have had wheel swaps over the years. Older trucks and vans often carry replacement wheels that no longer match the original fitment intent.

Inner-tube requirements on 1973 GMC tires depend on the specific tire, not just the vehicle. Most sizes here are not explicitly marked either way in the tire description, while at least one E78-14 option for the 1973 GMC Vandura is clearly identified as tubeless. That means tube status can vary by product and should not be assumed from size alone. The wheel design also matters, because an older rim may have been built around tube-type service even when a modern reproduction tire is available in tubeless form.

A careful 1973 GMC owner should check the actual sidewall marking of the chosen tire and inspect the wheel before final assembly. If the wheel is original, rusty, pitted, or of uncertain type, a tube conversation should include a knowledgeable installer rather than an assumption based on appearance. This is especially important on vehicles that have seen decades of use, restoration, or wheel changes. Tube choice, valve stem condition, and wheel condition all need to work together for a dependable setup.

A 1973 GMC should be stored in a cool, dry, dark space away from direct sunlight, electric motors, welders, chargers, and other ozone-producing equipment. Tires should be kept at proper inflation, the vehicle should be moved periodically to avoid prolonged loading in one spot, and long-term storage on damp ground should be avoided. Bias-ply tires, which make up most 1973 GMC applications, are especially prone to temporary flat-spotting when they sit. The radial applications in LR78-15, GR70-14, and HR78-15 generally tolerate static storage differently, but they still need protection from age and environmental exposure.

If a 1973 GMC will sit for months, many owners either roll it a short distance occasionally or support the vehicle in a way that reduces constant load on the tires. Storage habits matter as much on a lightly used collector as they do on a daily driver because age, ozone, and UV exposure work even when the odometer does not. Clean, dry sidewalls and stable inflation go a long way toward preserving both appearance and service life on vintage-style reproductions.

Tires on a 1973 GMC should be judged more by age than by mileage. Collector vehicles often wear tires slowly, but the rubber can still age out, harden, or crack long before the tread is gone. A sensible rule is to begin evaluating them closely once they reach the five- to seven-year range and to give serious replacement consideration around 10 years, even if they still look presentable from a distance. The DOT date code on the sidewall is the best starting point for that conversation.

A lightly driven 1973 GMC can fool its owner because a tire may still have plenty of tread but no longer have the flexibility or sidewall condition it once did. Service life also depends on storage, inflation habits, road exposure, and whether the vehicle carries heavy loads. The practical approach is to keep a written record of installation dates, inspect regularly, and replace aged tires before a long trip forces the decision. Age management is one of the most important habits in vintage vehicle care.

Tires on a 1973 GMC should be inspected before every drive and again before any extended outing. Look for sidewall cracking, weather checking, bulges, embedded debris, uneven wear, and pressure loss. On 16-, 16.5-, and truck-oriented applications, also pay close attention to old repairs and any signs of overload stress. If the setup uses tubes or may use tubes depending on the tire and wheel combination, valve stems and slow air loss deserve extra attention as part of the inspection routine.

Frequent inspection matters because many 1973 GMC vehicles are driven irregularly, which means problems can appear while the truck, van, or coupe utility is sitting still. A tire that looked fine at the last event may develop a crack or lose pressure during storage. Before a highway run, include the spare in the inspection and confirm that all four road tires match the intended trip. Vintage vehicles reward routine checks, and tires are one of the easiest places to catch trouble early.

A 1973 GMC C/K Pickup would have been fitted originally with bias-ply tires in one of several truck-appropriate size families, depending on wheel diameter and duty level. Sizes associated with the model include 700-15, G78-15, H78-15, L78-15, 700-16, 750-16, 875-16.5, 950-16.5, 800-16.5, and 10-16.5, while LR78-15 represents a radial-format option associated with the model range as well. In period terms, bias-ply construction remained the default expectation for many truck applications in 1973. Exact original size can vary with wheel package, payload intent, and how the truck was ordered.

For a true restoration, use the surviving placard, original paperwork, build information, or unrestored examples to narrow the correct size for that particular 1973 GMC C/K Pickup. Sidewall style also matters because a blackwall working truck restoration and a more dressed pickup can call for very different visual treatment even within the same nominal size. Marque clubs and model-specific literature are the best places to confirm market- and equipment-level detail. That research is worth doing before defaulting to the most common size in the broader model range.

Correct tire fitment absolutely matters when showing a 1973 GMC, especially in judged restoration classes. Judges and knowledgeable enthusiasts often notice whether the size family, wheel diameter, construction type, and sidewall treatment match the era and the personality of the vehicle. A radial where a bias-ply presentation is expected, a redline on a utility truck, or a commercial blackwall on a dressier passenger-style van can all look out of place. Even when the tire physically fits, it may still weaken authenticity.

The standard is not always identical from one event to another, so the safest path is to align the tire with the exact way the 1973 GMC is being restored. A Sprint may justify performance-style sidewalls, while a work-oriented Vandura or pickup may be better served by a more utilitarian blackwall look. If the vehicle is being built for concours-style judging, check event rules and consult marque specialists before making a final choice. Construction, sidewall style, and size all contribute to the finished impression.

For the 1973 GMC Sprint in G70-14, Firestone Wide Oval and Goodyear Custom Wide Tread share the same published maximum load of 1620 pounds at 32 psi, but they differ in sidewall presentation and wheel-width coverage. Firestone versions appear in redline, RWL, and pin white stripe styles and show a 6.50 to 7.00-inch rim-width range. Goodyear Custom Wide Tread appears in redline form and covers a broader 6.0 to 8.0-inch rim-width range. That makes them similar in era and category but different in cosmetic character and wheel compatibility envelope.

A Sprint owner choosing between them should start with the wheel already on the car and the exact visual goal for the build. If the car has a wider wheel, the Goodyear range may be useful; if the desired look centers on a particular Firestone sidewall treatment, that can steer the choice instead. Neither decision should be made on brand name alone. On a vehicle like the 1973 GMC Sprint, sidewall style is a major part of the period-correct presentation, and wheel width should be confirmed before final selection.

1973 GMC tires can be safe for highway use when they are the correct size, in sound condition, properly inflated, and used within their published limits. One explicit speed marking appears on the Avon 700-16C at L, which corresponds to a 75 mph ceiling. Many other 1973 GMC tires here are traditional bias-ply or bias-look radial reproductions without a modern speed-letter emphasis in the naming, so condition and proper application matter as much as outright speed capability. On a vintage GMC, brakes, steering, suspension, and alignment are often just as important to real-world road safety as the tire itself.

The practical takeaway is to match expectations to the vehicle. A well-sorted 1973 GMC used for normal cruising can be entirely enjoyable on the highway, but a 50-year-old truck or van should not be treated like a modern half-ton or SUV simply because it wears new tires. Check pressures, inspect for age cracking, and make sure all four tires are the same intended size family before a long run. If sustained higher-speed driving is part of the plan, pay special attention to the exact tire construction and any published speed marking.

Inflation pressure on a 1973 GMC depends on the exact tire size and product. Published examples include 700-15 at 32 psi on several passenger-style versions, G78-15 at 32 psi, H78-15 at either 32 psi or 45 psi depending on the tire, L78-15 at 32 psi, 700-16 at 36 psi on some versions, 750-16 at 40 or 48 psi depending on brand, 950-16.5 at 60 psi, 800-16.5 at 60 psi on one version, 10-16.5 at 60 psi, G70-14 at 32 psi, and E78-14 as high as 60 psi on one truck-oriented application. Those figures belong to the individual tire and should not be transferred from one size to another.

Use the original owner's manual or placard as the baseline for the vehicle, then compare that guidance with the inflation information tied to the exact reproduction tire being used. A 1973 GMC fitted with a passenger-style whitewall and one fitted with a commercial blackwall may need very different pressures even if the wheel diameter is the same. That is why pressure should always be matched to the actual tire and intended load. Overinflation and underinflation both affect ride, wear, and handling on vintage chassis.

Before a longer drive in a 1973 GMC, inspect every tire for cracks, cuts, bulges, punctures, and uneven wear, then verify cold inflation pressure and confirm that the spare is usable. Look closely at valve stems, especially if the setup may involve tubes or older wheels. On heavier-duty 16- and 16.5-inch applications, also make sure the tires match the intended load and that no wheel has visible damage or severe corrosion. A long drive is not the time to discover an old repair or a tire that has been slowly losing air in storage.

Tires are only one part of the pre-trip routine on a 1973 GMC, but they are the part that touches the road and often reveals problems first. Include the rest of the vehicle in the check: brakes, steering play, fluid levels, lights, and cooling system condition all matter on a truck, van, SUV, or Sprint that may only be driven occasionally. If the vehicle has sat for months, a short local test drive before the main trip is wise. That gives the tires and the rest of the chassis a chance to show issues early.