In 1973 Porsche offered two very different sports car experiences: the rear-engined 911, already established as the marque’s flagship, and the mid-engined 914, which delivered a lighter, more accessible take on German performance. That matters when choosing tires, because 1973 Porsche models used three radial sizes across the range rather than one universal fitment. The real choice comes down to identifying whether you have a 911 or a 914 first, then deciding whether you need the narrower stock-style metric radial or the wider 185/70R15 fitment used on the 911. Confirming the model and the actual 15-inch wheel on the car is the best first step before narrowing down products.
Which Tire Size Is Right for Your 1973 Porsche
Three tire sizes were used across 1973 Porsche vehicles, and they vary by model rather than applying across the entire range. All three are 15-inch radials, so the key decision is identifying the correct model and then confirming which 15-inch wheel and size your car uses. Understanding that distinction before choosing a product saves time and helps you match the tire to the car correctly.
Year(s): 1973|Fit(s): 911, 914|Construction: Radial|Rim: 15 in
165R15 is a metric radial with a 165-millimeter nominal section width and a 15-inch rim diameter; in this older Euro-metric format, the aspect ratio is conventionally around 80-series even though it is not written into the code. It is available from Coker Classic, American Classic, Firestone, and BFGoodrich in wide whitewall, narrow whitewall, and blackwall styles. This is the shared size across both 1973 Porsche models, making it the key option for owners aiming to stay with the narrower radial fitment used on either a 911 or a 914.
Year(s): 1973|Fit(s): 911|Construction: Radial|Rim: 15 in
185/70R15 is a metric radial with a 185-millimeter section width, a stated 70-series profile, and a 15-inch rim diameter. This size is specific to the 1973 Porsche 911 rather than universal across the year and make, and it is available from Michelin, Dunlop, Avon, and BFGoodrich in blackwall and wide whitewall styles; speed ratings vary by product, with V-rated options carrying a 149 mph ceiling. It suits 911 owners who need the wider low-profile radial size associated with that model’s fitment rather than the narrower shared metric radial.
Year(s): 1973|Fit(s): 914|Construction: Radial|Rim: 15 in
155R15 is a metric radial with a 155-millimeter nominal section width and a 15-inch rim diameter, using the older Euro-metric convention where the profile is typically around 80-series when no aspect ratio is written. This size is specific to the 1973 Porsche 914, and it is available from Firestone and Michelin in blackwall form; tube status and speed ratings vary by product, with T-rated versions at 118 mph and H-rated versions at 130 mph. It is the right choice for a 914 owner who needs the narrower 15-inch radial size tied to that model rather than the broader 911 fitment.
Because all three sizes use a 15-inch rim diameter, wheel compatibility usually comes down to confirming the wheel’s width range and the exact size the car was set up to use.
1973 Porsche Models
Two Porsche models are covered for 1973. They do not all share the same tire sizes, so identifying whether you have a 911 or a 914 matters before choosing a tire. Select a model below to narrow the fitment history and see the tire options that match that specific Porsche.
1973 Porsche 911
The 1973 Porsche 911 represents the last year of the early long-hood era and remains one of the most sought-after classic 911 generations. Its tire choices reflect the 911’s more performance-oriented character, with both 165R15 and the wider 185/70R15 mounting on 15-inch wheels. That makes model identification especially important if a car has been restored, upgraded, or set up differently over the years.
The 1973 Porsche 914 brought mid-engine balance and a distinct targa-bodied design to Porsche’s lineup, giving buyers a very different experience from the 911. Its tires mount on 15-inch wheels as well, but the model uses narrower radial sizes than the 911. That narrower sizing is part of what gives the 914 its light, responsive feel and should be considered when choosing a replacement set.
Twenty-five products are available across three tire sizes for 1973 Porsche vehicles. 165R15 includes 14 radial choices from Coker Classic, American Classic, Firestone, and BFGoodrich with blackwall, narrow whitewall, and wide whitewall styles; 185/70R15 includes 4 radials from Michelin, Dunlop, Avon, and BFGoodrich; 155R15 includes 7 radials from Firestone and Michelin in blackwall form. Confirm the exact size first, since tube requirements and speed ratings can vary within a given size.
These FAQs focus on how 1973 Porsche tire sizing differs between the 911 and 914, how older metric radial codes translate into practical choices, and what to check for sidewall style, tube status, speed rating, and long-term collector-car care.
Size Basics & Fitment
What tire sizes fit 1973 Porsche vehicles?
1973 Porsche vehicles used three radial sizes: 165R15, 185/70R15, and 155R15. The 911 uses 165R15 and 185/70R15, while the 914 uses 155R15 and 165R15. All three sizes mount on 15-inch rims, but the approved rim-width range changes by size where published. 165R15 fits 4.50- to 6.00-inch rims, 185/70R15 appears on products suited to 4.5- to 6.5-inch rims, and 155R15 appears on products suited to 4.00- to 5.50-inch rims.
That means year and make alone are not enough for a confident choice on a 1973 Porsche. You need to identify whether the car is a 911 or 914, then confirm the wheel width and the size already on the car before choosing a replacement. That step matters especially on restored cars, because wheel swaps and period-style upgrades are common on both models.
What does 165R15 mean on a 1973 Porsche tire?
On a 1973 Porsche, 165R15 is an older Euro-metric radial size. The 165 refers to a nominal section width of 165 millimeters, the R denotes radial construction, and the 15 is the wheel diameter in inches. Because there is no aspect ratio written into the code, it follows the older convention generally associated with an approximately 80-series profile. This size appears on both the 1973 Porsche 911 and 1973 Porsche 914.
That code is easy to misread if you are used to modern sizes such as 185/70R15. The 165R15 format is narrower and taller in appearance than a lower-profile modern metric radial, which is part of why it suits many stock-looking classic Porsche setups. It is also the broadest style choice on this page, since it is available in blackwall, narrow whitewall, and wide whitewall forms.
Do all 1973 Porsche models use the same tire size?
No. The 1973 Porsche 911 and 1973 Porsche 914 overlap at 165R15, but they do not share the full size range. The 911 also uses 185/70R15, while the 914 also uses 155R15. All three are 15-inch radial sizes, so the main difference is not wheel diameter but the width and profile associated with each model’s setup.
That model split is important because a 911 owner shopping by year alone could end up looking at a 914-size tire, and the reverse is just as easy. If the car has been in long-term ownership, has aftermarket wheels, or has gone through restoration work, check the sidewall of the current tire and measure the wheel before making a final choice.
Buying the Right Tire
Should I choose the 165R15 or the 185/70R15 for my 1973 Porsche?
For a 1973 Porsche, that choice depends first on the model. Both sizes appear on the 911, but only 165R15 is shared across the full 1973 Porsche range, while 185/70R15 is a 911-only fitment. Both are radial tires, so this is not a bias-ply-versus-radial decision. The practical difference is that 185/70R15 is the wider, lower-profile metric radial, while 165R15 is the narrower older-style Euro-metric radial.
A stock or lightly restored 911 may call for one size or the other depending on its wheel setup and intended presentation. If your car is a 914, the decision is different altogether because 185/70R15 does not belong to that model here. The safest route is to start with the exact model and wheel, then choose the tire size that matches the car’s existing configuration or restoration target.
What sidewall styles are available for 1973 Porsche tires?
1973 Porsche tire choices include several sidewall styles depending on size. The 165R15 offers blackwall, narrow whitewall, and wide whitewall options. The 185/70R15 offers mostly blackwall choices plus a wide whitewall version, while the 155R15 is available in blackwall form. Because these are 1973 Porsche sports cars, blackwall tires are generally the most era-appropriate visual fit for mainstream restoration and enthusiast use.
Sidewall appearance changes the character of the car even when the size stays the same. A blackwall keeps the presentation closest to what most buyers expect from an early-1970s Porsche, especially on a 911 or 914 with a European sports-car look. Whitewall variants can still appeal to owners building a very specific period style, but they should be chosen intentionally rather than by size alone.
What brands make tires for 1973 Porsche vehicles?
Several brands cover 1973 Porsche fitments. The 165R15 is available from Coker Classic, American Classic, Firestone, and BFGoodrich. The 185/70R15 is available from Michelin, Dunlop, Avon, and BFGoodrich. The 155R15 is available from Firestone and Michelin, including Michelin X, XAS, and XAS-FF series options within that narrow metric radial size.
Brand choice matters because each one tends to bring a different look and character to the car, even when the nominal size is the same. Some options lean toward a straightforward blackwall sports-car appearance, while others add a more stylized sidewall. Once you have confirmed the correct size for your 1973 Porsche, compare brands by sidewall style, speed rating, and tube status rather than choosing by name alone.
Fitting & Setup
What rim width do 1973 Porsche tires require?
Rim-width recommendations for 1973 Porsche tires depend on the size. Products in 165R15 fit 4.50- to 6.00-inch rims. Products in 155R15 fit 4.00- to 5.50-inch rims. Products in 185/70R15 appear with fitment ranges of 4.5 to 6.0 inches on some tires and 5.00 to 6.50 inches on others, so that size requires closer attention to the exact tire being chosen.
That variation is why wheel width should be confirmed before ordering, especially on a 911 that may have received wider wheels over the years. A tire can share the same 15-inch rim diameter and still call for a different wheel-width range. Matching the tire to the wheel helps preserve proper sidewall shape, steering response, and overall appearance.
Do 1973 Porsche tires require inner tubes?
Inner-tube requirements on 1973 Porsche tires vary by size and by product. The 185/70R15 includes a tubeless marking on at least one product, while 155R15 includes both tube-type and tubeless versions depending on the specific Michelin product. The 165R15 products shown here do not carry a TT or TL marker in the size marking, so the exact construction and wheel combination should be confirmed on the specific tire and wheel being used.
That matters because tube choice is not something to assume from the size code alone on a classic Porsche. Original wheel design, restoration changes, and the exact tire selected all affect whether a tube is appropriate. If you are replacing only one or two tires, check the sidewall marking on the existing set so the new tire’s tube status matches the rest of the car.
Can the original 1973 Porsche wheels be used with all tire sizes?
All of the tire sizes used on 1973 Porsche vehicles here share a 15-inch rim diameter, so they all fit 15-inch wheels in principle. That does not make them interchangeable across every original wheel, because the acceptable rim-width range changes by size. Narrower sizes such as 155R15 and 165R15 suit narrower wheels, while 185/70R15 often calls for more wheel width depending on the product.
A 15-inch wheel is only the starting point. Before moving from one size to another, measure the wheel width or confirm it against the wheel itself so the tire is matched correctly. This is especially important on 1973 Porsche cars because both the 911 and 914 are frequently found with replacement wheels that differ from their original setup.
Maintenance, Storage & Longevity
How should I store a 1973 Porsche when the tires are fitted?
A 1973 Porsche should be stored in a cool, dry, dark space with the tires kept away from direct sunlight, electric motors, battery chargers, welders, and other ozone-producing equipment. Tire pressures should be kept at a healthy maintenance level during storage, and the car should be rolled periodically or placed on stands if it will sit for an extended period. Radial tires resist flat-spotting better than old bias-ply designs, but any collector tire benefits from reducing long periods of static load.
Good storage habits protect both appearance and structure. Sidewall cracking usually starts with heat, UV exposure, and ozone rather than mileage, which is why a lightly driven classic Porsche can still age out its tires. If the car is under a cover, make sure moisture is not trapped around the wheels and tires for months at a time.
How long do tires on a 1973 Porsche typically last?
On a 1973 Porsche, tire life should be judged by age and condition more than tread depth or mileage. A practical rule is to begin evaluating collector-car tires closely once they are around five to seven years old and to treat ten years as a serious replacement threshold even if they still look usable. The DOT date code on the tire sidewall is the best guide to its actual age.
That approach matters because many classic Porsche cars are driven only occasionally, so the tread can look fine long after the rubber has hardened. Aging affects grip, ride quality, and resistance to cracking. If a newly purchased 1973 Porsche still wears older tires with plenty of tread, age alone can be reason enough to plan for replacement.
How often should tires on a 1973 Porsche be inspected?
Tires on a 1973 Porsche should be checked before every drive and inspected more thoroughly before any longer outing. Look for sidewall cracking, cuts, bulges, uneven tread wear, objects embedded in the tread, and any sign that the tire is losing pressure between drives. If the tire or wheel setup uses tubes, the valve stem and tube-related hardware deserve the same attention because a slow leak can start there.
Frequent inspections are especially important on older sports cars because they often sit for long periods, then return to road use suddenly. A quick look around all four tires and the spare takes only a few minutes and can catch age-related problems early. If the steering feel changes or the car begins to pull, inspect the tires before assuming it is strictly a chassis issue.
Restoration & Authenticity
What tires were originally fitted to the 1973 Porsche 911?
The 1973 Porsche 911 would have been delivered in the radial-tire era, and the sizes associated with the model here are 165R15 and 185/70R15. That means a radial construction is the correct starting point for an authentic tire search on a 1973 Porsche 911. The exact size choice can vary with wheel equipment and market-specific setup, so originality work should focus on matching the car’s wheel and period presentation rather than assuming one universal 911 size.
For a restoration, size and sidewall appearance matter just as much as the fact that the tire is radial. A blackwall usually aligns best with the look most enthusiasts expect on an early-1970s 911. If you are chasing show-level accuracy, compare the wheel currently on the car with factory references and marque-club guidance before making a final tire decision.
Does correct tire fitment matter for showing a 1973 Porsche?
Yes, correct tire fitment matters on a 1973 Porsche because judges and knowledgeable enthusiasts notice size, construction, and sidewall appearance quickly. On a car from 1973, a radial tire is generally appropriate, but the exact size still needs to match the model and wheel. A 911 wearing a 914-size tire, or a car fitted with a sidewall style that clashes with its period character, can look obviously out of place even before close inspection.
Show standards vary by event, so the smart approach is to treat authentic fitment as a combination of correct size, correct construction type, and a sidewall style that suits the car’s market and presentation. National marque clubs and event judging manuals are the best places to confirm what a specific concours expects. That extra homework is worthwhile when the car is being judged at a high level.
What is the difference between Michelin XAS and Michelin XAS-FF for the 1973 Porsche 914?
For the 1973 Porsche 914 in 155R15, Michelin XAS and Michelin XAS-FF are both H-rated radial choices with a 130 mph speed ceiling, and both appear on 4.00- to 5.50-inch rim widths. The key difference here is tube status: Michelin XAS appears as 155HR15 82H TT, while Michelin XAS-FF appears as 155HR15 82H TL. Both are blackwall tires and both sit within the same narrow 15-inch fitment family.
That distinction matters because it affects how you plan the installation and what wheel setup you are working with. If your 914 still uses a wheel and tire combination intended for tube-type service, the XAS may align with that need. If you need a tubeless-marked alternative in the same basic size and speed class, the XAS-FF deserves a close look after wheel compatibility is confirmed.
Safety & Road Use
Are 1973 Porsche tires safe for highway driving?
1973 Porsche tires can be suitable for highway driving when they are the correct size, properly inflated, in sound condition, and used within their speed rating. The 155R15 includes T-rated products with a 118 mph ceiling and H-rated products with a 130 mph ceiling, while the 185/70R15 includes V-rated products with a 149 mph ceiling. Those figures are already beyond ordinary U.S. highway use, and on a classic Porsche the car’s own mechanical condition is just as important as the tire’s speed capability.
Highway safety on a 1973 Porsche is really a systems question. Good tires cannot compensate for tired suspension bushings, weak shocks, old brake hoses, or poor alignment. Before regular highway use, confirm the age and condition of the tires, then make sure the rest of the car is equally ready for the speeds and distances you plan to drive.
What inflation pressure should I use for 1973 Porsche tires?
Inflation pressure on 1973 Porsche tires should start with the vehicle manufacturer’s recommendation for the car and then be checked against the tire’s own maximum load and pressure information where it is published. On the tires here, 165R15 appears with load-and-pressure figures of 1168 to 1170 pounds at 35 to 36 psi, 185/70R15 includes a product at 1,257 pounds at 35 psi and another at 1,279 pounds, and 155R15 includes 1045 pounds at 44 psi on one product. Those numbers are not a blanket running-pressure recommendation for every Porsche application.
The key is not to transfer one tire’s pressure figure to another size just because both fit a 15-inch wheel. Porsche’s recommended front and rear pressures may differ by model and setup, especially on rear-engined cars such as the 911. Use the car’s factory guidance as your baseline, then confirm that your chosen tire is operating within its rated limits.
What should I check before taking a 1973 Porsche on a longer drive?
Before a longer drive in a 1973 Porsche, inspect all four tires and the spare for age cracking, cuts, bulges, abnormal wear, and correct inflation. Look closely at the sidewalls and valve stems, and if the tire setup uses tubes, pay extra attention to stems, sealing, and any signs of slow leakage. Make sure the tire size matches the wheel and that there is no rubbing or interference at full steering lock or full suspension movement.
Tires are only one part of the pre-drive routine on a classic Porsche, but they are among the most time-sensitive parts to inspect because age can degrade them even when the car has seen little mileage. A thorough check should also include brakes, wheel fasteners, fluid levels, belts, and lights. If the car has been sitting, take a short test drive first before committing to a full-distance outing.
