1973 Cadillac Tire Fitment Guide

1973 Cadillac vehicles use two tire sizes: 890-15 and L78-15. The 890-15 fits the 1973 Cadillac Commercial Series, while L78-15 fits the 1973 Cadillac Eldorado, Limousine, and Standard Models. Both sizes mount on 15-inch wheels. For 890-15, the available rim width range is 6.50 to 7.00 inches. For L78-15, the available rim width range is 5.50 to 8.00 inches.

That means year and make alone are not enough for a correct choice on a 1973 Cadillac. Commercial coachbuilt applications need the 890-15 fitment, while Cadillac passenger cars for this year center on L78-15. If the car has changed hands, been restored long ago, or wears non-original wheels, confirm the model first and then verify wheel width against the tire you plan to use.

On a 1973 Cadillac, 890-15 is a numeric bias-ply tire size. The 8.90 portion refers to the tire's nominal section width, and the 15 identifies the wheel diameter in inches. In this application, 890-15 belongs to the Commercial Series and reflects the larger, heavier-duty style of sizing often seen on professional-car and coachbuilt Cadillac chassis of the period.

A buyer looking at 890-15 should think first about model identity and vehicle role, not just appearance. It is the right starting point for a hearse, ambulance, or other Commercial Series Cadillac where larger period-correct bias-ply fitment matters. Once size is confirmed, the next choice becomes sidewall style, since both wide whitewall and blackwall versions are available in that size.

No. 1973 Cadillac models do not all use the same tire size. The Commercial Series uses 890-15, while the Eldorado, Limousine, and Standard Models use L78-15. Even though both sizes fit 15-inch wheels and both are bias-ply types in this year-make range, they are not interchangeable simply because the rim diameter matches.

That distinction is especially important with Cadillacs because the lineup covered both passenger luxury cars and professional-car chassis. If you are unsure whether your car falls under a standard passenger model or a commercial chassis, verify the model designation before choosing a tire. That one step prevents the most common year-make-level mistake on 1973 Cadillac fitment.

1973 Cadillac tire sidewall choices depend on size. The 890-15 used on the Commercial Series is available in wide whitewall and blackwall forms. The L78-15 used on Eldorado, Limousine, and Standard Models is available in blackwall, narrow whitewall, and wide whitewall styles. That gives passenger-car Cadillacs the broader visual range, while the Commercial Series stays closer to two distinct presentation choices.

For a 1973 Cadillac restoration, sidewall style changes the car's character almost as much as wheel cover or trim details. Wide whitewalls generally suit formal luxury presentation and period showroom appearance, while blackwalls can make a car look more restrained or more fleet-oriented depending on the model. If authenticity matters for judging, compare your choice against period photos, factory literature, and marque-specific restoration guidance.

Three brands cover 1973 Cadillac applications across the two sizes. The 890-15 size is available from Firestone and Avon, while L78-15 is available from Coker Classic and BFGoodrich. All of these options are bias-ply tires in this year-make range, so the brand decision comes down to size availability, sidewall style, and the presentation you want on the finished vehicle.

Brand choice matters most after the size is settled, because each size has its own mix of makers and sidewall treatments. A Commercial Series owner choosing 890-15 will compare Firestone wide whitewalls against an Avon blackwall, while an Eldorado or Standard Model owner in L78-15 has more whitewall variety. It is worth checking the sidewall marking and visual profile closely if the car is being restored to a specific look.

For 1973 Cadillac Commercial Series models, the 890-15 Firestone options carry a 2500-pound maximum load at 40 psi, fit 6.50- to 7.00-inch rims, and come in 3.00-inch or 5.00-inch wide whitewall form. The Avon Turbospeed 890-15 is a blackwall bias-ply tire with a 2,337-pound maximum load and an S speed rating, which corresponds to a 112 mph ceiling.

That creates a clear visual and specification split within the same size. Firestone favors the formal whitewall appearance many professional-car restorations call for, while Avon offers a blackwall presentation with an explicit speed rating. The right choice depends on whether your Commercial Series Cadillac is being finished for era-correct ceremonial appearance, subdued commercial styling, or regular road use within the vehicle's intended character.

Rim width depends on the tire size used on the 1973 Cadillac model. The 890-15 used on the Commercial Series fits a 6.50- to 7.00-inch rim width range. The L78-15 used on Eldorado, Limousine, and Standard Models fits a 5.50- to 8.00-inch rim width range. Both sizes are 15-inch tires, but the acceptable rim-width window is not the same.

That is why wheel diameter alone is not enough when setting up a vintage Cadillac. A tire can mount to the right 15-inch wheel diameter and still be poorly matched if the rim width is outside the tire's intended range. Before mounting, confirm the actual wheel dimensions on the car, especially if the wheels may have been swapped during a previous restoration or period customization.

Inner-tube status is not marked in a way that separates tube-type from tubeless across the 1973 Cadillac products, so the practical approach is to verify the exact tire's sidewall marking and the wheel's design before final assembly. Both 890-15 and L78-15 are bias-ply applications, and tube decisions on collector vehicles often depend on the specific tire construction and whether the original wheel is intended for tubeless service.

That matters most on older wheels that may have surface rust, pitting, or rim contours from an earlier era. A restorer should inspect the wheel carefully and confirm compatibility with the chosen tire before mounting. If the car retains original wheels, especially on a Commercial Series chassis or a formal passenger Cadillac that has sat for years, this is a worthwhile checkpoint before the tires go into service.

Original 1973 Cadillac wheels can only be shared between sizes if they are the correct 15-inch diameter and fall within the proper rim-width range for the intended tire. The 890-15 and L78-15 both use 15-inch rims, but 890-15 is tied to the Commercial Series while L78-15 belongs to Eldorado, Limousine, and Standard Models. Matching diameter does not make the sizes interchangeable across the entire Cadillac lineup.

For most owners, that means staying with the size associated with the model is the safest path. If a previous owner changed wheels, measure the wheel and confirm whether it suits the tire you plan to mount. This is especially important where passenger-car and coachbuilt Cadillac parts may have crossed over during decades of repairs, storage, or specialty-body refurbishment.

A 1973 Cadillac should be stored in a cool, dry, dark space with the tires kept away from direct sunlight, electric motors, battery chargers, furnaces, and other ozone-producing sources. Keep the tires properly inflated, roll the car periodically if possible, and avoid leaving one heavy corner loaded in the same spot for months at a time. Because these 1973 Cadillac fitments are bias-ply, flat-spotting during long static storage is more common than many modern drivers expect.

That is especially relevant on large Cadillacs, where vehicle weight can accentuate temporary shape changes after sitting. If the car will be stored for a season, moving it occasionally or using storage supports can help reduce stress on the casing. Clean storage habits also preserve whitewalls, which are a major visual feature on many 1973 Cadillac restorations.

On a 1973 Cadillac, tire age is usually more important than miles driven. Collector-car tires should be inspected regularly after about five to seven years of service, and replacement should be seriously considered as they approach ten years, even if tread depth still looks strong. The DOT date code, sidewall condition, and the tire's storage history all matter more than odometer mileage on a low-use classic.

Cadillacs that spend much of their life parked can fool owners into thinking the tires are still fresh because the tread is hardly worn. In reality, time, heat cycles, and environmental exposure harden the rubber and can weaken the structure. If the car is newly acquired and the tire age is uncertain, a careful date-code and condition check should happen before any meaningful road use.

Tires on a 1973 Cadillac should be inspected before every drive and more thoroughly before any longer outing. Check inflation, tread wear, sidewall cracking, cuts, bulges, embedded debris, and any signs that the tire is no longer holding pressure consistently. Because these are vintage-style bias-ply applications, it is also wise to keep an eye on age-related hardening and on valve-stem condition during routine checks.

A short pre-drive walkaround is often enough to catch problems before they become expensive or dangerous. On a collector Cadillac, that inspection should also include the spare, since it may be decades old even if it has never touched the road. If the car has been in storage, inspect the tires again after the first few heat cycles once driving resumes.

A 1973 Cadillac Eldorado uses the L78-15 size in this year-make range, and bias-ply construction is era-appropriate for the fitment shown here. L78-15 was also shared with 1973 Cadillac Limousine and Standard Models, which places the Eldorado squarely in Cadillac's passenger-car tire group for that year rather than the separate Commercial Series 890-15 application.

For a restoration, that gives you a strong starting point on both size and construction style. The remaining authenticity choice often comes down to sidewall presentation, since blackwall, narrow whitewall, and wide whitewall versions are available in L78-15. If you are chasing exact factory-delivery appearance for a particular market or trim presentation, period brochures and Cadillac marque specialists are the best final check.

Correct tire fitment absolutely matters when showing a 1973 Cadillac. Judges and knowledgeable enthusiasts often notice whether the car wears the proper size for its model, whether the construction type suits the era, and whether the sidewall treatment matches the character of the vehicle. On this year-make range, putting a Commercial Series tire size on a passenger Cadillac, or choosing the wrong whitewall style for the presentation, can change the car's visual authenticity immediately.

That does not mean every event uses the same standard, but it does mean tires should be part of the restoration plan rather than an afterthought. A formal Cadillac often looks dramatically different on blackwalls, narrow whites, and wide whites. If the car will be judged, consult the event rules and Cadillac club guidance so your tire choice supports the level of originality the show expects.

For 1973 Cadillac models using L78-15, Coker Classic offers blackwall and wide whitewall versions, while BFGoodrich appears here in a 1.00-inch narrow whitewall. The Coker Classic L78-15 tires carry a 1,970-pound maximum load at 32 psi and fit 5.50- to 8.00-inch rims, with weights around 30 to 31 pounds. The BFGoodrich L78-15 also carries a 1,970-pound maximum load at 32 psi, fits the same rim-width range, and weighs 31 pounds.

The practical difference is less about fitment than about appearance and brand character. A narrow whitewall gives a distinct early-1970s visual feel, while blackwall and wider whitewall options can push the car toward a sportier or more formal presentation. If your 1973 Cadillac is being judged, compare the sidewall width you choose against period-correct photos for the exact look you want to replicate.

1973 Cadillac tires can be suitable for highway driving when they are the correct size, properly inflated, in sound condition, and used within their design limits. The 890-15 Avon option carries an S speed rating, which corresponds to a 112 mph ceiling. The other 1973 Cadillac products here are bias-ply tires without a speed letter shown in the size marking, so they should be treated as vintage-style fitments meant to be driven with the restraint appropriate to an early-1970s luxury vehicle.

In real use, the tire is only one part of the equation on a large Cadillac. Brakes, suspension condition, steering play, wheel bearings, and alignment often matter as much as the tire itself at normal road speeds. A well-sorted car on fresh, properly chosen tires can be very enjoyable on modern roads, but highway confidence comes from the whole vehicle being ready, not the tire alone.

Inflation pressure should follow the vehicle manufacturer's recommendation for the model and the tire maker's guidance for the specific reproduction tire. Among the available 1973 Cadillac products, 890-15 Firestone tires carry a maximum load of 2,500 pounds at 40 psi, the 890-15 Avon carries 2,337 pounds, and L78-15 tires carry a maximum load of 1,970 pounds at 32 psi. Those figures describe the tire's rated capacity point and should not be treated as a universal operating pressure for every 1973 Cadillac.

The right approach is to begin with the factory recommendation for the exact Cadillac model, then make sure the chosen tire is being used within its published limits. Never transfer a pressure number from 890-15 to L78-15, or from a Commercial Series vehicle to an Eldorado or standard passenger Cadillac. Tire pressure affects ride, handling feel, and wear, so it deserves model-specific confirmation.

Before a longer drive in a 1973 Cadillac, inspect each tire for sidewall cracking, weather-checking, cuts, bulges, uneven wear, and proper inflation. Make sure the valve stems are sound, the tread is free of damage, and the spare is usable rather than simply present. A longer trip also justifies checking for age-related issues that may not show up during short local use, especially on a car that spends much of its time parked.

Tires are only one part of pre-trip preparation on a 1973 Cadillac. It is equally wise to look over brakes, steering response, cooling system health, and fluid levels before heading out. Large, comfortable Cadillacs can make a long drive feel effortless, which is exactly why a thorough inspection beforehand is worth the time.