BMW entered 1978 with a lineup that spanned compact sport sedans, executive four-doors, and grand touring coupes, all carrying the brand’s growing reputation for precise road manners and European engineering. For U.S. enthusiasts, 1978 BMW marks a period when model identity mattered because tire sizing followed the role of each chassis rather than a one-size-fits-all approach. Across four model groups, four radial sizes appear, with some models sharing a conventional 14-inch fitment while the 733i also reaches into Michelin TRX territory with a metric-size alternative. Before choosing a tire for 1978 BMW, confirm the exact model first, then verify whether your car uses a standard-inch wheel or the TRX metric wheel system.
Which Tire Size Is Right for Your 1978 BMW
Four tire sizes are used across 1978 BMW vehicles, and they vary by model rather than carrying across the full range. The key decision is first identifying the correct model and wheel diameter, especially because the 733i can use either a conventional 14-inch radial size or a metric TRX radial. Sorting that out before choosing a product saves time and helps match the tire to the car and wheel you actually have.
Year(s): 1978|Fit(s): 320i & 320iA|Construction: Radial|Rim: 13 in
185/70R13 is a radial metric size with a 185-millimeter section width, a 70-series aspect ratio, and a 13-inch rim diameter. It is available from BFGoodrich, Avon, and Dunlop in blackwall, redline, and wide whitewall form, and speed ratings vary by product, including H at 130 mph and V at 149 mph. This size is specific to the 320i and 320iA rather than the full 1978 BMW range. It suits owners who want to stay with the compact E21 fitment while choosing between a more sporting blackwall look and period-style sidewall treatments.
195/70R14 is a radial metric size with a 195-millimeter section width, a 70-series aspect ratio, and a 14-inch rim diameter. It is available in Dunlop blackwall form, with a V speed rating carrying a 149 mph ceiling and a maximum load capacity of 1,356 pounds. This size is shared by the 530i and 530iA as well as the 633 CSi and CSiA, so it is not universal across 1978 BMW but it does span both the 5 Series and 6 Series applications here. It is the straightforward choice for owners keeping those larger conventional-wheel cars in an era-appropriate radial fitment.
Year(s): 1978|Fit(s): 733i|Construction: Radial|Rim: 14 in
205/70R14 is a radial metric size with a 205-millimeter section width, a 70-series aspect ratio, and a 14-inch rim diameter. It is available from Maxxis and BFGoodrich with narrow whitewall, RWL, dual-redline, and redline sidewall treatments; speed ratings vary by product, including S at 112 mph, while load capacity reaches 1,433 pounds at 35 psi on several offerings. This size is specific to the 733i among 1978 BMW models using conventional 14-inch wheels. It works for owners who want to keep their 7 Series on standard-inch rims while tailoring the look from understated to distinctly period-styled.
220/55R390 is a radial metric size with a 220-millimeter section width, a 55-series aspect ratio, and a 390-millimeter rim diameter. It is available from Michelin in blackwall form as a tubeless TRX tire, with a W speed rating carrying a 168 mph ceiling. This size is specific to 733i models equipped with the TRX metric wheel system and does not interchange with conventional 14-inch wheels. It is the correct path for owners preserving an original TRX-equipped car and wanting to keep that distinctly late-1970s BMW/Michelin setup intact.
Four 1978 BMW model groups are covered here, and tire size changes by model rather than staying consistent across the range. That matters because a 320i, a 530i, and a 733i do not simply share the same fitment, and the 733i adds the extra wrinkle of either conventional 14-inch wheels or Michelin TRX metric wheels. Select your model below for model-specific fitment history and products.
1978 BMW 320i & 320iA
The 320i was BMW’s compact sport sedan for the U.S. market and helped define the early 3 Series as a nimble, driver-focused car with tidy proportions and direct road feel. Its tires mount on 13-inch rims in this application, setting it apart from the larger BMW sedans and coupes of the same year.
The 530i represented BMW’s midsize executive sedan formula before the 5 Series grew larger, blending sporting character with more cabin space and touring comfort than the 3 Series. Its fitment uses a 14-inch rim, matching the broader stance expected of the chassis without moving into the 7 Series’ alternate metric-wheel territory.
The 633 CSi was BMW’s elegant grand touring coupe, prized for its shark-nose styling and long-distance road-car character. Its tires also mount on 14-inch rims, sharing size with the contemporary 530i while serving a distinctly coupe-oriented model with its own restoration and appearance priorities.
Associated Tire Sizes:
195/70R14 — radial, factory-style grand touring fitment
The 733i sat at the top of BMW’s sedan range in 1978, bringing early 7 Series luxury and high-speed Autobahn influence to the U.S. market. It can ride on either conventional 14-inch wheels with a 205/70R14 tire or on BMW’s period Michelin TRX metric wheel system with a 390mm rim, so wheel type is the first thing to verify on the car.
Fourteen products are available across four tire sizes for 1978 BMW vehicles. The 185/70R13 has four products from BFGoodrich, Avon, and Dunlop in radial construction with blackwall, redline, and wide whitewall styles; 195/70R14 has one Dunlop blackwall radial; 205/70R14 has four radial choices from Maxxis and BFGoodrich with narrow whitewall, RWL, dual-redline, and redline styling; and 220/55R390 has one Michelin blackwall radial. Confirm your size first, and check the specific product for speed rating and tube status where those details matter.
These answers cover the model-by-model size differences across 1978 BMW, the special TRX metric fitment used on some 733i cars, available sidewall looks, and the maintenance habits that matter when a collector BMW is driven occasionally rather than daily.
Size Basics & Fitment
What tire sizes fit 1978 BMW vehicles?
1978 BMW vehicles use four radial tire sizes across four model groups. The 320i and 320iA use 185/70R13, the 530i and 530iA use 195/70R14, the 633 CSi and CSiA also use 195/70R14, and the 733i uses either 205/70R14 or 220/55R390 depending on wheel type. Rim diameters are 13 inches, 14 inches, or 390 millimeters, so the year and make alone are not enough to choose correctly.
That means the first fitment question on a 1978 BMW is always model identification, and on a 733i it is also wheel identification. Where rim width recommendations are available, 185/70R13 products span roughly 4.5 to 6.5 inches, 205/70R14 products span roughly 5.0 to 7.5 inches, and the TRX 220/55R390 fits specific metric-width TRX rims. Matching the tire to the wheel you actually have is more important here than trying to compare all 1978 BMW models as though they shared one standard setup.
What does 185/70R13 mean on a 1978 BMW tire?
On a 1978 BMW, 185/70R13 is a metric radial size. The 185 is the nominal section width in millimeters, 70 is the aspect ratio, R means radial construction, and 13 is the wheel diameter in inches. In this year and make, that size belongs to the 320i and 320iA, making it the compact 3 Series fitment rather than a larger BMW sedan or coupe size.
Understanding that code helps you avoid crossing over into a different BMW model’s tire just because it looks close on paper. It also explains why sidewall choices can vary so much within one size, from blackwall to redline or wide whitewall, even though the underlying dimensions stay the same. Once the code is clear, the remaining choice is usually visual character and intended driving style, not whether the size itself belongs on another 1978 BMW model.
What does 220/55R390 mean on a 1978 BMW tire?
On a 1978 BMW, 220/55R390 is a metric radial size used with the Michelin TRX wheel system. The 220 is the nominal section width in millimeters, 55 is the aspect ratio, R means radial construction, and 390 is the rim diameter in millimeters rather than inches. That last number is the critical point, because a 390mm TRX wheel is not the same thing as a 14-inch wheel.
This size matters most on the 1978 BMW 733i, where some cars were equipped with TRX wheels and others used conventional 14-inch wheels with 205/70R14 tires. Owners sometimes assume those two sizes are close enough to interchange, but the wheel systems are fundamentally different. If your 733i still has TRX wheels, keep the car on the correct metric tire size unless you are deliberately converting to a different wheel package.
Do all 1978 BMW models use the same tire size?
No, 1978 BMW models do not all use the same tire size. The 320i family uses 185/70R13, the 530i and 633 CSi families share 195/70R14, and the 733i uses either 205/70R14 or 220/55R390. Every size here is radial, but the dimensions and wheel diameters vary enough that one model’s fitment should not be assumed for another.
That makes model identity a practical fitment checkpoint, not just a catalog detail. A buyer with a 530i or 633 CSi can focus on the shared 195/70R14 option, while a 320i owner needs to stay with the 13-inch fitment and a 733i owner needs to confirm whether the car is on standard-inch or TRX metric wheels. Taking two minutes to verify that point prevents the most common ordering mistake for 1978 BMW tires.
Buying the Right Tire
Should I choose the 205/70R14 or the 220/55R390 for my 1978 BMW?
For a 1978 BMW 733i, the choice between 205/70R14 and 220/55R390 is determined by the wheel on the car, not by preference alone. The 205/70R14 fits conventional 14-inch wheels, while the 220/55R390 fits the Michelin TRX metric wheel system with a 390mm rim. Both are radial tires, but they are not interchangeable because the wheel diameters are different in both unit of measure and actual design.
If your 733i still wears TRX wheels and you want to preserve that late-1970s BMW presentation, the 220/55R390 keeps the proper system intact. If the car has standard 14-inch wheels, the 205/70R14 is the correct route. Looking at the wheel itself before comparing tread or sidewall style is the essential first step, because no tire choice can overcome a mismatch between an inch-based wheel and a metric TRX wheel.
What sidewall styles are available for 1978 BMW tires?
1978 BMW tire choices include more than plain blackwalls. The 185/70R13 for the 320i is available in blackwall, redline, and wide whitewall form, while the 205/70R14 for the 733i appears in narrow whitewall, RWL, dual-redline, and redline versions. The 195/70R14 used on the 530i and 633 CSi and the 220/55R390 TRX size for the 733i are blackwall options.
For most restoration-minded BMW owners, blackwall remains the most natural visual fit for a late-1970s German car, especially on executive sedans and coupes. Redline, dual-redline, whitewall, and raised white letter treatments can create a custom or period-accessory look, but they change the visual tone of the car more noticeably than many buyers expect. Choosing the sidewall is often less about raw fitment and more about whether you want an understated European presentation or a more stylized collector-car appearance.
What brands make tires for 1978 BMW vehicles?
1978 BMW tire coverage comes from several brands depending on size. The 185/70R13 size is available from BFGoodrich, Avon, and Dunlop; the 195/70R14 size is available from Dunlop; the 205/70R14 size is available from Maxxis and BFGoodrich; and the 220/55R390 TRX size is available from Michelin. That spread reflects the fact that different BMW models and wheel systems of the period call for very different tire personalities.
Brand choice usually becomes easier once the size is settled. A 320i owner has a wider mix of sporting blackwall and period-style sidewall options, while a 530i or 633 CSi owner in 195/70R14 is really choosing within a narrower, more focused touring-style fitment. For a 733i with TRX wheels, Michelin is part of the original character of that system, so preserving the car’s wheel setup naturally narrows the field.
Fitting & Setup
What rim width do 1978 BMW tires require?
Rim width depends on the tire size used on the specific 1978 BMW model. For 185/70R13, suitable rim widths run from 4.5 to 6.5 inches depending on the tire. For 205/70R14, suitable rim widths run from 5.0 to 7.5 inches depending on the tire. The 220/55R390 TRX tire fits specific metric TRX rim widths, including 135mm, 150mm, and 180mm, while 195/70R14 products here do not add a rim-width range.
That range matters because a tire can have the right diameter and still be a poor choice for the wheel if width falls outside the manufacturer’s approved window. Measure the wheel already on the car or confirm its original specification before making a final selection, especially on modified cars. TRX-equipped 733i models deserve extra attention because metric wheel widths and metric rim diameter make them a separate system from standard inch-based BMW wheels.
Do 1978 BMW tires require inner tubes?
Most 1978 BMW tire choices here are radial designs without a tube-type marking, while the Michelin 220/55R390 for TRX-equipped 733i models is explicitly tubeless. That means tube use is not a universal requirement across the year and make. The important point is that tube status should be checked on the exact product and wheel combination rather than assumed from the car alone.
On a late-1970s BMW with original-style tubeless wheels in good condition, tubeless fitment is usually the expected path. Even so, wheel condition, valve-stem sealing, and corrosion in the bead area can matter just as much as the tire itself. If a wheel has been restored, repaired, or is of uncertain origin, confirm the intended tube or tubeless setup before mounting so the tire, wheel, and valve hardware work together correctly.
Can the original 1978 BMW wheels be used with all tire sizes?
No, original 1978 BMW wheels cannot be treated as universal across all tire sizes used that year. The 320i uses a 13-inch tire, the 530i and 633 CSi use 14-inch tires, and the 733i may use either a 14-inch tire or a 390mm TRX tire. Because the diameters differ, one original wheel style does not automatically accept another model’s tire size.
The 733i is the most important example because a conventional 14-inch wheel and a 390mm TRX wheel are separate systems even though the sizes may sound close. For the rest of the range, staying with the model-correct wheel diameter is the first rule before comparing brand or sidewall style. If the car has changed hands or been modified over the years, inspect the actual wheel stamping or measure it instead of relying on assumptions tied to the badge.
Maintenance, Storage & Longevity
How should I store a 1978 BMW when the tires are fitted?
A stored 1978 BMW should be kept in a cool, dry, dark space away from direct sunlight, electric motors, welders, furnaces, and other ozone sources that accelerate rubber aging. Tires should rest on a clean surface, be kept at proper inflation, and the car should be moved periodically or supported in a way that reduces long-term flat spotting. Radials generally tolerate storage better than old bias-ply designs, but they still age from environment as much as from miles.
Collector BMWs often sit longer than modern daily drivers, so storage habits affect tire life in a very visible way. A car left in one spot for months can develop temporary vibration, while sunlight and heat work silently into the sidewalls even when tread depth still looks healthy. If your 1978 BMW is a seasonal car, a simple routine of pressure checks, occasional rolling, and protection from UV and ozone goes a long way toward preserving both appearance and road manners.
How long do tires on a 1978 BMW typically last?
Tires on a 1978 BMW should be judged more by age and condition than by mileage alone. A good rule is to begin evaluating them closely once they reach about five to seven years of age, and to consider replacement as they approach ten years even if tread remains. The DOT date code on the sidewall tells you when a tire was made, which is especially important on collector cars that may cover very few miles each season.
Many vintage BMW owners are surprised to find that the oldest-looking part of the tire is not the tread but the rubber compound itself. A lightly driven 320i, 530i, 633 CSi, or 733i can easily age out a set of tires before wearing it out. If the car spends more time parked than driven, build your replacement decision around age, cracking, and carcass condition rather than the assumption that low mileage automatically means long remaining life.
How often should tires on a 1978 BMW be inspected?
Tires on a 1978 BMW should be inspected before every drive and again before any longer trip. Look for sidewall cracking, tread separation, punctures, bulges, uneven wear, and pressure loss. Pay attention to valve stems as well, since an aging stem can create the same kind of trouble as a damaged tire, especially on a car that spends time parked between outings.
A quick inspection matters more on a collector car than many owners realize because age-related issues can develop without obvious mileage wear. A 733i on TRX tires, a 320i on compact 13-inch radials, or a 633 CSi prepared for a weekend event all benefit from the same routine: visual check, pressure check, and a brief look at the spare. That habit catches small problems early and helps turn a longer drive into a confidence check instead of a roadside surprise.
Restoration & Authenticity
What tires were originally fitted to the 1978 BMW 320i?
A 1978 BMW 320i was originally part of an era when radial tires were standard European practice, and the correct size here is 185/70R13. That size matches the 320i and 320iA fitment for the year and preserves the compact 3 Series’ intended wheel diameter and overall stance. Original-equipment branding could vary by market and delivery history, so the safest authenticity reference points are size, radial construction, and appropriate sidewall appearance.
For a restoration, the question is usually not whether the 320i should be on a radial, but which visual treatment best suits the car’s intended presentation. A blackwall typically aligns most naturally with the late-1970s European look, while redline or whitewall treatments create a more personalized period impression. If your car is being judged or restored to a particular market delivery standard, a BMW club or marque specialist can help confirm the most appropriate sidewall style for that exact car.
Does correct tire fitment matter for showing a 1978 BMW?
Correct tire fitment matters on a 1978 BMW because show and concours evaluation often takes size, construction, wheel compatibility, and sidewall appearance into account. A 320i on the wrong diameter, a 530i or 633 CSi wearing a visibly non-period sidewall treatment, or a 733i converted away from its original TRX presentation can all change how authentic the car appears. Even when judging is informal, experienced enthusiasts notice tire details quickly.
The practical standard is to match the tire to the way the car is being presented. A survivor, concours restoration, and driver-grade car can each justify slightly different choices, but the more serious the authenticity goal becomes, the more important details like wheel system, size, and sidewall style become. Before a judged event, compare your tires against period photos, factory literature, and BMW club guidance so you are not losing points over something as visible as the contact patch.
What is the difference between BFGoodrich Silvertown Radial and Dunlop SP Sport Aquajet for the 1978 BMW 320i?
For a 1978 BMW 320i in 185/70R13, BFGoodrich Silvertown Radial and Dunlop SP Sport Aquajet differ in both presentation and specification. The BFGoodrich options appear in redline and wide whitewall form, carry a 1,135-pound maximum load at 35 psi, and fit rim widths from 5.00 to 6.50 inches. The Dunlop SP Sport Aquajet is a blackwall sporting radial with a V speed rating, a 149 mph ceiling, and a 1,047-pound maximum load figure.
That makes the BFGoodrich line more visually tied to period-style specialty sidewalls, while the Dunlop leans toward a cleaner sporting look that suits an owner who wants a more understated European presentation. Neither choice changes the fact that the 320i stays on the same 185/70R13 fitment, but they do change the character of the car. If appearance matters as much as driving feel, compare the sidewall treatment first and the speed-rating character second.
Safety & Road Use
Are 1978 BMW tires safe for highway driving?
Yes, 1978 BMW tires in these sizes can be suitable for highway driving when they are fresh, correctly fitted, properly inflated, and matched to sound wheels. Speed ratings where stated include S at 112 mph on some 205/70R14 products, H at 130 mph on some 185/70R13 products, V at 149 mph on some 185/70R13 and 195/70R14 products, and W at 168 mph on the 220/55R390 Michelin TRX. All of these are radial constructions, which suits the late-1970s BMW character well.
Real-world highway confidence in a 1978 BMW depends on more than the tire alone. Brakes, suspension bushings, steering components, wheel alignment, and the condition of the spare all matter just as much on a car of this age. A fresh set of correctly matched tires is a strong foundation, but the safer approach is to treat tire condition as one part of an overall roadworthiness check rather than assuming the speed rating alone answers the question.
What inflation pressure should I use for 1978 BMW tires?
Inflation pressure on a 1978 BMW should follow the vehicle manufacturer’s recommendation for the model and wheel setup, then be checked against the tire manufacturer’s own rated information for the exact product. Some of these tires include load-and-pressure figures, such as 185/70R13 at 1,135 pounds at 35 psi, 205/70R14 at 1,433 pounds at 35 psi, and 195/70R14 at 1,356 pounds. Those figures describe the tire’s rated capacity point, not automatically the pressure you should run on every BMW application.
That distinction matters because pressure is tuned to the car’s weight distribution, suspension behavior, and intended use, not just the tire’s maximum rated load point. A 320i, 530i, 633 CSi, and 733i should not all be assumed to want the same inflation setting even when tire construction is similar. Start with the car’s factory recommendation, adjust only within the tire maker’s approved limits, and recheck pressures regularly when ambient temperatures change.
What should I check before taking a 1978 BMW on a longer drive?
Before a longer drive in a 1978 BMW, inspect all four tires and the spare for cracking, punctures, uneven wear, bulges, and proper inflation. Confirm that the tire size matches the wheel on the car, which is especially important on a 733i where conventional 14-inch and TRX metric wheel systems both appear. Check valve stems, lug torque, and overall wheel condition along with tire age, since an older tire can look usable while still being past its comfortable service life.
A longer outing in a late-1970s BMW should also include a broader mechanical check beyond the contact patch. Brake feel, cooling system behavior, fluid levels, belts, lights, and wiper performance all deserve attention before the trip starts. Tires are the only part of the car touching the road, but on a collector BMW they work as part of an older system, so a careful pre-drive routine is the best way to enjoy the car without adding avoidable risk.
