1978 Porsche Tire Fitment Guide

1978 Porsche vehicles use seven radial sizes across four model lines. The 911 uses 185/70R15 and 215/60R15, the 924 uses 165R14 and 185/70R14, the 928 uses 215/60R15 and 225/50R15, and the 930 uses 205/55R16 and 225/50R16. Rim diameter changes with the model, so 924 tires mount on 14-inch wheels, 911 and 928 tires mount on 15-inch wheels, and 930 tires mount on 16-inch wheels.

That split means year and make alone are not enough for a confident tire choice on a 1978 Porsche. You need to identify the exact model first, then confirm whether the car uses a single-size setup or paired sizes front and rear. Where rim-width guidance is available, it also varies by size, so wheel measurement is worth checking before final selection.

On a 1978 Porsche, 165R14 is a euro-metric radial size used on the 924. The 165 refers to nominal section width in millimeters, the R identifies radial construction, and the 14 is the wheel diameter in inches. Because no aspect ratio is written into the size, it conventionally indicates an 80-series profile in period European tire terminology.

That matters because 165R14 has a different look and stance than a lower-profile modern metric size. It preserves the narrower, taller sidewall character associated with many late-1970s European cars, and it should not be treated as interchangeable with every other 14-inch Porsche size. If your 924 currently wears a different marking, compare it to the actual wheel and the car’s intended setup before changing sizes.

No, 1978 Porsche models do not use one common tire size. The 911 and 928 overlap at 215/60R15, but the 924 uses only 14-inch sizes, and the 930 uses only 16-inch sizes. Several models also use two different sizes rather than one, which is especially important on the performance-focused 930.

The practical takeaway is simple: identify the model before you decide on a tire, and confirm whether the car uses matched or staggered sizing. Porsche’s late-1970s lineup covered a broad span from entry-level transaxle coupe to high-speed turbo car, so tire fitment followed the mission of the individual model rather than a shared corporate standard.

1978 Porsche tire options span more than one sidewall style, depending on size. Blackwall is the most common presentation across every size, while 185/70R15 and 185/70R14 also appear in wide whitewall form, and 215/60R15 is offered in blackwall, wide whitewall, redline, and raised white letter form. The 16-inch 930 sizes stay entirely in blackwall configurations.

For most 1978 Porsche restorations and driver-grade cars, blackwall is the appearance that aligns most naturally with the marque’s late-1970s sporting identity. Whitewall, redline, and RWL versions create a more custom or market-specific look, so they are best chosen deliberately rather than by accident. If authenticity matters, compare the sidewall treatment to period photos, factory literature, or a knowledgeable Porsche club source.

1978 Porsche tires are available from Michelin, Dunlop, Avon, BFGoodrich, Pirelli, Vredestein, and American Classic, depending on size. The 14-inch 924 sizes draw heavily from European brands, the 15-inch 911 and 928 sizes mix European and American choices, and the 16-inch 930 sizes center on BFGoodrich and Michelin. Brand coverage changes with the exact size rather than staying uniform across the entire Porsche range.

That brand spread gives owners room to prioritize the character they want from the car. Some buyers lean toward period European names on 924, 911, or 928 applications, while others prefer a particular tread or sidewall style in the same size. The best approach is to pick the correct size first, then narrow the field by brand heritage, sidewall appearance, and speed rating.

For a 1978 Porsche 911 in 185/70R15, Michelin XWX and BFGoodrich Silvertown Radial differ in both presentation and specification. The Michelin XWX is a blackwall radial in 185/70VR15 with a 5.00 to 6.50-inch rim-width range and tubeless marking, while the BFGoodrich Silvertown Radial uses a 2.25-inch whitewall in the same nominal size, carries a 5.00 to 6.50-inch rim-width range, and shows a 1,257-pound maximum load at 35 psi.

That makes the choice less about basic fit and more about the look and character you want from the car. The Michelin has the more traditional European sporting appearance, while the BFGoodrich creates a very different visual statement with its whitewall. Either way, verify that the wheel width falls within the tire’s approved range before making a final decision.

Rim-width guidance varies by size on 1978 Porsche applications. 185/70R15 fits 4.5 to 6.5-inch rims depending on the tire, 215/60R15 fits 5.5 to 7.5-inch rims, 165R14 fits 4.0 to 6.0-inch rims depending on brand, 185/70R14 fits 4.5 to 6.5-inch rims, 205/55R16 fits 5.5 to 7.5-inch rims, and 225/50R16 fits 6.0 to 8.0-inch rims. Those ranges are size-specific and should not be transferred from one tire size to another.

Wheel diameter is only the first checkpoint. Two tires may both fit a 15-inch wheel, for example, yet want different wheel widths for proper sidewall shape and tread support. If your Porsche has replacement wheels, measure the wheel width directly or confirm the stamping before committing to a tire, especially on staggered 930 applications.

Most 1978 Porsche tire choices are radial tubeless designs, and several products explicitly carry TL marking, including examples in 185/70R15, 165R14, 185/70R14, 205/55R16, and 225/50R16. Within some sizes, tube status varies by product because not every tire carries the same marking. That means tube use should be confirmed against the exact tire and the wheel’s construction rather than assumed from size alone.

On a Porsche with original wheels, the wheel condition matters just as much as the tire marking. A wheel designed for tubeless service and in sound condition may not need a tube when matched with a TL tire, while an older or specialty wheel can change that conversation. Checking the sidewall marking and wheel type together is the cleanest way to avoid setup mistakes.

Original 1978 Porsche wheels cannot be treated as universally interchangeable across all sizes, because the range spans 14-, 15-, and 16-inch diameters. A 924 wheel cannot accept a 911 or 928 15-inch tire, and a 930 16-inch tire is its own category again. Even where two models share a 15-inch diameter, such as the 911 and 928 at 215/60R15, wheel width still needs to match the tire’s approved range.

That is especially important on cars that have changed hands several times and may now wear later wheels or aftermarket replacements. Start by confirming wheel diameter, then verify wheel width against the exact size you plan to run. On a staggered 930, check front and rear separately rather than assuming the whole car uses one wheel and tire specification.

A 1978 Porsche should be stored in a cool, dry space away from direct sunlight, electric motors, welders, battery chargers, and other ozone-producing equipment that can age rubber prematurely. Keep the tires properly inflated, roll the car periodically if possible, and avoid leaving it parked for long stretches on wet concrete or contaminated surfaces. Radial tires resist flat-spotting better than older bias-ply designs, but they still benefit from movement during long storage.

Storage habits matter because collector cars often age their tires by time more than mileage. If the Porsche will sit for months, many owners use tire cradles or lift the weight off the tires entirely, provided the car is supported correctly. After storage, inspect each tire closely before driving, especially around the sidewalls, valve stems, and bead area.

On a 1978 Porsche, tire life is usually judged by age and condition more than tread depth. Collector-car tires often deserve close evaluation around five to seven years of age, and many owners treat ten years as a practical outer limit even if the tread still looks serviceable. The DOT date code on the sidewall is the best starting point for understanding the tire’s age.

A low-mileage weekend Porsche can fool owners because the tread may remain deep while the rubber hardens or cracks with time. That is why a visually clean tire is not automatically a healthy one. If the car has older tires and you plan to drive it regularly or at highway speeds, age alone may justify replacement even before wear bars become relevant.

Tires on a 1978 Porsche should be inspected before every drive and again before any longer outing. Look for sidewall cracking, punctures, bulges, uneven wear, low inflation, and signs that the tire has been rubbing or running out of alignment. If your tire has a tubeless marking, also pay attention to valve stem condition and any slow pressure loss over time.

Frequent checks matter on older Porsches because age-related issues can appear long before a tire is worn out. A quick walk-around and pressure check can catch a developing problem while it is still minor. Before a road trip, add a closer inspection of the spare, the jacking equipment, and the tire pressures after the car has been sitting overnight.

A 1978 Porsche 911 would have been fitted with radial tires, not bias-ply tires, as Porsche had long embraced radial construction by that period. Within this year group, the 911 uses 185/70R15 and 215/60R15 on 15-inch wheels. Original-equipment branding can vary by market, wheel package, and period replacement history, so size and construction are usually the first authenticity points to confirm.

For a restoration, getting the size family, wheel diameter, and overall sidewall appearance right usually matters more than chasing a single brand without supporting evidence. If the car is being judged, consult factory literature, period road tests, and marque-club sources to verify what was appropriate for your exact configuration. That is especially useful when a car has changed wheels during its lifetime.

Correct tire fitment matters on a shown 1978 Porsche because judges and knowledgeable enthusiasts notice size, wheel diameter, construction type, and sidewall appearance very quickly. A 924 on a mismatched 15-inch fitment, a 930 without its proper 16-inch staggered look, or a late-1970s Porsche wearing a conspicuous custom sidewall style can change the car’s authenticity profile even if the tire physically fits.

For local events, that may only affect how correct the car appears. For marque-focused judging, it can influence scoring more directly, especially if originality is a key category. If you are building for concours presentation, verify the exact model’s expected tire size and compare sidewall treatment to period photography before choosing between blackwall and more decorative alternatives.

For a 1978 Porsche 930 in 225/50R16, BFGoodrich g-Force Sport COMP-2 and Michelin Pilot Sport share the same 16-inch fitment and 6.0 to 8.0-inch rim-width range, but they differ in rating details and weight. The BFGoodrich carries a 92W speed rating, equal to 168 mph, with a 1,389-pound maximum load at 51 psi, while the Michelin Pilot Sport carries a 92Y speed rating, equal to 186+ mph, and tubeless marking. The Michelin is also heavier at 30 pounds versus 25 pounds for the BFGoodrich.

That comparison makes this a nuanced choice rather than a simple fitment decision. Both suit the same wheel diameter and width window, but the sidewall marking and speed capability are not identical. If your 930 is being restored with an eye toward period-correct presentation, compare tread style and brand character as closely as the raw size, then make sure the wheel width and intended use agree with the tire you choose.

Yes, 1978 Porsche tires can be appropriate for highway driving when they are the correct size, in sound condition, and used within their speed rating. Depending on size and product, available ratings include S to 112 mph, H to 130 mph, V to 149 mph, W to 168 mph, and Y to 186+ mph. On many 1978 Porsche applications, the tire’s speed rating exceeds what normal U.S. highway use would ever demand.

Real-world safety still depends on more than the sidewall code. A 1978 Porsche may be limited more by age, alignment, suspension condition, braking condition, or old fuel and ignition components than by the tire itself. Before sustained highway driving, make sure the car is mechanically sorted and that all four tires are evenly matched in size, condition, and inflation.

Inflation pressure on a 1978 Porsche should follow the vehicle manufacturer’s recommendation first, then be checked against the tire’s own maximum-load marking where one is present. Examples include 1,257 pounds at 35 psi for one 185/70R15 product, 1,411 pounds at 35 psi for 215/60R15, 1,102 pounds at 51 psi for one 165R14, 1,201 pounds at 35 psi for one 185/70R14, 1,356 pounds at 51 psi for one 205/55R16, and 1,389 pounds at 51 psi for one 225/50R16.

Those figures are not blanket running pressures for every Porsche or every tire in the same size. They show the load relationship at the tire’s stated maximum, not necessarily the ideal cold pressure for your car. Use the owner’s manual or factory pressure decal for the baseline, then confirm that the selected tire’s load capacity is appropriate for the application.

Before a longer drive in a 1978 Porsche, inspect each tire for cracks, punctures, tread damage, bulges, and uneven wear, then verify cold pressures on all four corners and the spare. Confirm that the front and rear sizes are correct for the model, especially on a 930, and pay attention to valve stem condition on tubeless setups. If the tires are several years old, look closely at the inner sidewalls as well as the outer faces.

Tires are only one part of the preparation, but they are the part that most directly connects the car to the road. A longer outing in an older Porsche also calls for checking wheel fasteners, brakes, fluid levels, belts, lights, and fuel-system condition. Starting with a thorough tire inspection reduces the chances that a preventable rubber-related issue cuts the trip short.