The 1968 Opel lineup brought German small-car sensibility to buyers who wanted compact dimensions, light weight, and efficient road manners at a time when imported cars were gaining real traction in the U.S. market. In that year, 1968 Opel centered this tire discussion around the Kadett, a practical and well-known entry point into European motoring. Tire choice is unusually straightforward here because one model uses one size, 155R13, in radial construction on a 13-inch wheel. The key step before choosing a tire is confirming that your Kadett still carries the correct 13-inch wheels and deciding whether you want a touring-oriented period European radial for restoration-minded driving.
Which Tire Size Is Right for Your 1968 Opel
The 1968 Opel range uses one tire size, and it is shared across the model covered here rather than varying by model. That makes the main decision less about comparing multiple fitments and more about confirming the correct 13-inch wheel and choosing the radial product that best matches your driving and restoration goals. Understanding that distinction up front saves time and helps you choose the right tire with confidence.
Year(s): 1968|Fit(s): Kadett|Construction: Radial|Rim: 13 in
155R13 is a euro-metric radial size with a 155-millimeter nominal section width and a 13-inch rim diameter; because no aspect ratio is stated, it conventionally represents an 80-series radial. This size is available from Michelin and Dunlop in Blackwall form, and the products carry H speed ratings with a 130 mph ceiling; tubeless marking appears on some versions, so tube status varies by product. For a 1968 Opel Kadett, this is the correct year-and-model size and suits owners who want an authentic European radial character rather than a larger fitment change.
One model is covered for 1968 Opel. Because the Kadett uses a single tire size for this year and make, the focus is not sorting through multiple fitments but choosing the right product style within that size for your car's restoration goals and driving habits. Select the model below for model-specific fitment history and tire options.
1968 Opel Kadett
The 1968 Opel Kadett was Opel's compact, efficient family car, known in the U.S. for tidy proportions and a distinctly European driving feel. Its tires mount on 13-inch wheels, and the year-specific fitment centers on one radial size, which keeps size selection simple while still leaving room to choose between period-flavored touring products.
Two products are available across one tire size for 1968 Opel vehicles. The 155R13 comes in radial construction from Michelin and Dunlop, both in Blackwall styling. Confirm your size first, and check the individual tire's sidewall marking because tube status can vary between products.
These FAQs cover the 1968 Opel tire questions that matter most for a small German sedan of this era: how to read 155R13, what changes from one radial product to another, wheel and tube considerations, and how to care for collector-car tires between drives.
Size Basics & Fitment
What tire sizes fit 1968 Opel vehicles?
The 1968 Opel fitment covered here is straightforward: the Kadett uses 155R13 radial tires. That size mounts on a 13-inch wheel, and the available 155R13 products cover rim widths from 4.00 to 5.50 inches where that specification is stated. Since only one size applies across the 1968 Opel model covered on this page, there is no same-year size split to sort through.
That simplicity is helpful, but it is still smart to confirm the actual wheels on the car before replacing tires. Many vintage imports have changed hands several times, and wheel swaps are common. If your Kadett still carries its proper 13-inch wheels, 155R13 is the place to start. From there, your real choice is between the available radial products rather than between multiple factory size paths.
What does 155R13 mean on a 1968 Opel tire?
On a 1968 Opel, 155R13 is a euro-metric radial size. The 155 refers to a nominal section width of 155 millimeters, the R identifies radial construction, and the 13 is the wheel diameter in inches. When a size appears as 155R13 without a written aspect ratio, it conventionally refers to an 80-series radial profile.
That code matters because it tells you both the tire's basic proportions and the wheel diameter it fits. A 155R13 is not interchangeable with a 14-inch or 12-inch tire, and it should not be confused with older U.S. numeric sizing. For a 1968 Opel Kadett, reading the code correctly helps you stay with the proper compact European fitment rather than moving into a different diameter or profile by mistake.
Do all 1968 Opel models use the same tire size?
Within the 1968 Opel coverage here, yes. The Kadett uses 155R13, and there is no alternate same-year Opel size in this model group to compare against. That means year and make alone are nearly enough to narrow the fitment, with the final confirmation coming from the actual wheel diameter on the car.
For a buyer, that removes much of the confusion common to larger domestic lineups where tire size changes by trim, body style, or engine package. On a 1968 Opel Kadett, the decision is usually not which of several factory sizes applies, but which 155R13 radial best fits your intended use. A car aimed at preservation, touring, or regular fair-weather driving can all start from the same size baseline.
Buying the Right Tire
What sidewall styles are available for 1968 Opel tires?
The 155R13 tires available for 1968 Opel fitment come in Blackwall styling. That appearance suits the Kadett's compact European character and aligns well with the understated look many imported cars of the late 1960s carried. There is no same-size whitewall or other sidewall treatment in this fitment group, so the visual choice stays simple.
For most owners, that means the buying decision stays focused on tire brand, construction details, and intended use rather than decorative sidewall styling. Blackwall also tends to be the cleanest visual fit for a modestly trimmed German compact unless a particular regional or show-standard preference applies. If your goal is a factory-appropriate appearance, Blackwall is the natural direction for a 1968 Opel Kadett.
What brands make tires for 1968 Opel vehicles?
Michelin and Dunlop both offer 155R13 radial tires for 1968 Opel fitment. Michelin's option is the XAS-FF series, while Dunlop's is the SP Sport Aquajet. Both reflect the kind of European radial thinking that matches the Kadett's period, compact dimensions, and road-car mission.
Brand choice here is less about chasing a radically different fitment and more about selecting the product character you want within the correct size. Some owners prefer a Michelin nameplate for period European cachet, while others may be drawn to Dunlop's sporting heritage. Either way, staying within 155R13 keeps the car in the right dimensional neighborhood for a 1968 Opel Kadett.
What is the difference between Michelin XAS and Dunlop SP Sport Aquajet for the 1968 Opel?
For a 1968 Opel Kadett, both the Michelin XAS and Dunlop SP Sport Aquajet are 155R13 radial Blackwall tires with H speed ratings. Both also weigh 20 pounds in this size, and both fit 13-inch wheels. The Michelin carries a clearly stated rim-width range of 4.00 to 5.50 inches and a tubeless marking, while the Dunlop product includes a 937-pound max load figure.
That means the difference is not a dramatic size or speed split, but the finer details of how each product is presented and matched to the wheel on your car. If your main concern is wheel-width compatibility, confirm your wheel against the product you choose. If you are comparing them for restoration flavor, tread styling and brand heritage may influence the decision more than raw dimensions.
Fitting & Setup
What rim width do 1968 Opel tires require?
The 1968 Opel Kadett uses 155R13 tires on 13-inch wheels, and the published rim-width range for the Michelin version of that size is 4.00 to 5.50 inches. That gives a useful working range for a stock-style compact wheel. Since wheel width can vary on older cars, that number should be checked against the actual wheel before mounting a new tire.
Rim width matters because it affects how the tire sits on the wheel, which in turn influences appearance and road behavior. A wheel that is too narrow or too wide for the tire can compromise the intended shape of the casing. If your Kadett still has original or stock-dimension wheels, you are usually in the right neighborhood, but measuring the wheel is still the best final step before committing.
Do 1968 Opel tires require inner tubes?
Inner tube requirements for 1968 Opel 155R13 tires vary by product. Some versions carry a tubeless sidewall marking, while others do not make that point the same way in the size designation. Because of that, tube use should be confirmed against the specific tire you choose and the condition and design of the wheel itself.
That distinction matters most on older wheels, especially if the rims have corrosion, pitting, or design features that affect air retention. A tubeless-marked tire on a sound wheel may not need a tube, while another setup may benefit from a different approach. Before mounting, check the sidewall marking on the exact product and make sure the wheel, valve stem, and sealing surfaces are appropriate.
Maintenance, Storage & Longevity
How should I store a 1968 Opel when the tires are fitted?
A 1968 Opel should be stored in a cool, dry, dark space away from direct sunlight, electric motors, welders, battery chargers, and other ozone-producing equipment. Keep the tires clean, maintain proper inflation, and move the car periodically if it sits for long stretches. Radial tires generally tolerate storage better than bias-ply tires, but they still age faster when exposed to heat, light, and long static loading.
If the Kadett will sit for months at a time, consider increasing attention to flat spotting, moisture control, and the condition of the floor beneath the tires. Some owners roll the car a short distance every few weeks, while others use stands for longer off-season storage after supporting the car correctly. The goal is to reduce casing stress and preserve both ride quality and appearance between driving seasons.
How long do tires on a 1968 Opel typically last?
On a 1968 Opel, tire life is usually determined more by age than by mileage. Collector-car tires should be evaluated closely once they reach about five to seven years of age, and many owners begin serious replacement consideration around the ten-year point regardless of remaining tread depth. The DOT date code on the tire sidewall is the practical way to confirm age.
That guidance is especially important for a lightly driven Kadett that may cover few miles each year. A tire can look decent at a glance yet still lose flexibility and safety margin with time. If you are putting the car back on the road after a long rest, age should be part of the first inspection, right alongside cracks, hardening, and signs that the tire has spent years under-inflated or stationary.
How often should tires on a 1968 Opel be inspected?
Tires on a 1968 Opel should be inspected before every drive and again before any longer trip. Check inflation, tread condition, sidewall cracking, weather checking, cuts, bulges, and anything that suggests impact damage or air loss. If your chosen setup uses tubes, valve stems and the tube-related sealing points deserve extra attention as part of the routine.
Frequent inspection makes sense because collector vehicles often spend more time parked than driven, and storage-related aging can appear long before tread wears out. A quick walkaround before a casual drive can catch a low tire or developing crack early. Before a weekend tour or highway outing, take a more careful look and include the spare so the car is supported by five serviceable tires, not just four.
Restoration & Authenticity
What tires were originally fitted to the 1968 Opel Kadett?
A 1968 Opel Kadett would have been built in the era when radial tires were becoming strongly associated with European passenger cars, and the correct fitment covered here is 155R13 in radial construction. That makes a period European-style radial the right starting point for an authentic look and feel. Original-equipment brand can vary by market and delivery history, so size and construction are the more dependable first checks.
For restoration work, getting the dimensions and construction type right usually matters more than chasing a brand assumption that may not apply to every market. If your car is headed for marque judging or a highly exacting restoration, compare your tire choice with factory literature, period photos, and Opel club resources. Those sources can help settle market-specific details without pulling the car away from the correct 155R13 radial baseline.
Does correct tire fitment matter for showing a 1968 Opel?
Correct tire fitment absolutely matters when showing a 1968 Opel, especially in events that value factory presentation and era accuracy. Judges and knowledgeable enthusiasts notice size, construction type, overall tire profile, and sidewall appearance. On a late-1960s European compact like the Kadett, an appropriately sized radial Blackwall generally looks far more in character than an oversized or visibly modernized alternative.
That does not mean every show applies the same standard, but obvious departures from the proper size family can distract from an otherwise careful restoration. If your goal is concours-level authenticity, verify the tire against period Opel references and the expectations of the event you plan to enter. A local cruise night may be more forgiving, while marque-focused judging can place greater emphasis on dimension and period-correct appearance.
What is the difference between Michelin XAS and Dunlop SP Sport Aquajet for the 1968 Opel?
For restoration-minded 1968 Opel owners, Michelin XAS and Dunlop SP Sport Aquajet share the same 155R13 radial size, Blackwall styling, 13-inch fitment, H speed rating, and 20-pound weight. The Michelin carries a stated 4.00 to 5.50-inch rim-width range and a tubeless marking, while the Dunlop includes a published 937-pound load figure. The core authenticity question is less about size correctness and more about which period-style European radial presentation you prefer.
That makes this a fine-detail decision rather than a major fitment fork. Either product keeps the car in the right dimensional family for a Kadett, but a restorer may favor one brand's historical image, sidewall treatment, or tread character over the other. If you are preparing the car for judged events, compare the exact sidewall appearance to period references and consult Opel enthusiasts who know how specific your target standard will be.
Safety & Road Use
Are 1968 Opel tires safe for highway driving?
The 155R13 tires available for 1968 Opel fitment carry H speed ratings, which correspond to a 130 mph ceiling. That is far beyond normal U.S. highway use and gives ample headroom from a tire-speed standpoint for a properly maintained Kadett. In real-world vintage driving, the car's brakes, suspension condition, steering, and overall mechanical state are usually more important limiting factors than the tire's speed symbol.
Safe highway use still depends on age, condition, inflation, and correct mounting. A decades-old tire with good tread is not automatically a trustworthy road tire, and neither is a fresh tire mounted on a damaged wheel. Before regular highway use, make sure the tires are healthy, the alignment is sensible, and the rest of the car is ready for sustained speed in the way a late-1960s compact should be driven.
What inflation pressure should I use for 1968 Opel tires?
Inflation pressure for 1968 Opel tires should be set with two references in mind: the factory recommendation for the car and the tire maker's own load-and-pressure guidance for the exact tire. One 155R13 option in this fitment group carries a published max load of 937 pounds, but that figure should not be treated as a universal running pressure target. Pressure is not something to transfer casually from one product to another.
Start with the vehicle's original handbook or factory placard information, then compare that baseline with the reproduction or specialty tire manufacturer's recommendations if they differ. The right operating pressure supports the car's weight, steering feel, and tire wear pattern without over-inflating a light vintage chassis. Check pressures cold, and revisit them after a wheel or tire change rather than assuming the old setting remains appropriate.
What should I check before taking a 1968 Opel on a longer drive?
Before a longer drive in a 1968 Opel, inspect each tire for cracking, cuts, bulges, uneven wear, and proper inflation, then check the spare as carefully as the four on the car. Look closely at valve stems and confirm that the wheels are clean and sound where the tire seals. If your chosen setup uses tubes, include tube-related hardware and leakage checks in the pre-trip routine.
Tire preparation is only one part of the equation on a late-1960s import. A Kadett headed for a tour should also have its brake system, wheel bearings, cooling system, and basic tune-up items reviewed before the trip. The reason is simple: a healthy set of correctly fitted 155R13 tires works best when the rest of the chassis is equally ready for distance. Reliable road manners come from the whole package, not the tire alone.
