The 1968 Fiat 850 belongs to the era when small-displacement European cars delivered lively character through light weight, compact dimensions, and simple mechanical charm. Whether in Coupe, Sport, Spider, or Sedan form, the 850 rewards owners who pay attention to details that preserve its balance and appearance. Tire choice matters here because this model uses different 12-inch and 13-inch fitments depending on sub-model, with both period-style bias-ply sizes and radial alternatives in play. Available choices range from traditional whitewall bias-ply tires to blackwall radial options from well-known European brands. The right selection starts with the exact body style, wheel diameter, and the kind of driving or restoration presentation you want.
Which Tire Size Is Right for The 1968 Fiat 850
The 1968 Fiat 850 uses four primary tire sizes across its covered configurations, and the first step is confirming whether the car is a Coupe, Sport, Spider, or Sedan. Fitment also splits by wheel diameter, with 13-inch tires used on the Coupe, Sport, and Spider, and 12-inch tires used on the Sedan. Once that is settled, the decision becomes whether to stay with the period-style bias-ply fitment or evaluate the radial size used on that same sub-model group.
155R13 is a Euro-metric radial size: 155 is the nominal section width in millimeters, R identifies radial construction, and 13 is the wheel diameter in inches. On the 1968 Fiat 850, this radial size is used on Coupe, Sport, and Spider applications and offers a more modern sizing convention than the companion bias-ply fitment. Available choices include Michelin and Dunlop products, both offered as blackwall radials in distinctive series. This size is the one to evaluate if the car has the 13-inch wheel setup and the goal is a radial tire within the correct general fitment family.
560-13 is a numeric bias-ply size in which 5.60 refers to the tire's nominal section width in inches and 13 identifies the wheel diameter. For the 1968 Fiat 850 Coupe, Sport, and Spider group, it represents the traditional bias-ply fitment and preserves the period-style sizing language many restorers expect to see on a small European car of this era. Product choices include BFGoodrich and Firestone options, with narrow whitewall and wide whitewall sidewall treatments available across classic bias-ply series. This is the size to consider when maintaining a more traditional construction and vintage visual character on a 13-inch setup.
155R12 is a Euro-metric radial size, with a 155-millimeter nominal section width, radial construction, and a 12-inch rim diameter. On the 1968 Fiat 850, this size applies to the Sedan and should not be confused with the 13-inch fitments used on the Coupe, Sport, and Spider. Its format reflects a modern radial approach rather than the older numeric bias-ply system. This size is the relevant starting point when the car is a Sedan on 12-inch wheels and the owner wants to stay within the proper radial fitment family for that configuration.
5.50-12 is a numeric bias-ply size, with 5.50 describing the nominal section width in inches and 12 indicating the wheel diameter. For the 1968 Fiat 850 Sedan, this is the period-style bias-ply fitment and it belongs to a different wheel diameter than the Coupe, Sport, and Spider tire group. The older numeric format is typical of the era and points toward a restoration-oriented tire choice rather than a later radial sizing convention. This is the size to use as the basis for selection when the car is a Sedan and the goal is to retain its traditional 12-inch bias-ply presentation.
Sub-model fitment matters on the 1968 Fiat 850 because the Coupe, Sport, and Spider share one wheel-and-tire family while the Sedan uses another. Checking the exact body style first keeps 12-inch and 13-inch fitments from being mixed, and it also clarifies whether you are comparing the right bias-ply and radial options.
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1968 Fiat 850 Coupe, Sport, Spider
The 1968 Fiat 850 Coupe, Sport, and Spider use the 13-inch tire group, with both 155R13 radial and 560-13 bias-ply fitments associated with these models. That gives owners a choice between a more traditional period-style bias-ply presentation and a radial alternative, while still requiring confirmation of wheel size and overall fitment goals.
The 1968 Fiat 850 Sedan uses the 12-inch tire group rather than the 13-inch setup used on the sportier body styles, with 155R12 radial and 5.50-12 bias-ply fitments tied to it. Tire selection starts with preserving that 12-inch configuration and then deciding whether the car's use and appearance goals favor bias-ply or radial construction.
Bias-Ply to Radial Tire Conversion for the 1968 Fiat 850
For the original 560-13 tire size, three radial-equivalent options are available. 155R13 is the 80-series metric radial equivalent, P155/75R13 is the P-metric 75-series radial equivalent, and P155/70R13 is the P-metric 70-series radial equivalent. These choices move from classic Euro-metric radial sizing to progressively lower-profile P-metric alternatives. A recommended rim-width range of 4 to 5 inches applies to this equivalent group, and wheel width, overall dimensions, and vehicle clearance should all be checked before making a conversion.
Modern Radial Equivalents
155R13
Equivalent 80-series Metric Radial (560-13)
P155/75R13
Equivalent P-metric 75-series Radial (560-13)
P155/70R13
Equivalent P-metric 70-series Radial (560-13)
Important Considerations When Replacing Bias Ply With Radial
Compare overall diameter and section width carefully to ensure proper fit.
Verify recommended rim range (4-5 in) and load needs match your vehicle specifications.
Check fender clearance, steering clearance, and stance before installation.
Consider suspension condition and intended road use when choosing equivalents.
Important Fitment Notes
The tire sizes listed on this page assume factory-standard vehicle configuration. The following modifications may affect tire fitment and are not reflected in this guide:
Suspension changes (lowering, lift kits, spring replacements)
Body alterations (fender modifications, custom bodywork)
If your vehicle has been modified from factory specifications, verify tire clearance before purchase.
Best 1968 Fiat 850 Tires for Sale
Available 1968 Fiat 850 tire choices include Michelin and Dunlop blackwall radials in 155R13, along with BFGoodrich and Firestone bias-ply options in 560-13. The bias-ply selection adds narrow whitewall and wide whitewall treatments across classic tire series, giving buyers both construction and appearance choices.
These 1968 Fiat 850 tire FAQs focus on the details that matter most: sub-model size differences, 12-inch versus 13-inch wheel fitment, bias-ply and radial choices, radial equivalents for 560-13, appearance options, and the checks to make before road use.
Tire Size & Fitment
What tire size fits a 1968 Fiat 850?
A 1968 Fiat 850 can use 155R13 and 560-13 on Coupe, Sport, and Spider models, while the Sedan uses 155R12 and 5.50-12. That means there is not one universal tire size for every 1968 Fiat 850, because fitment changes with the sub-model and wheel diameter.
The most important step is confirming whether the car is a Sedan or part of the Coupe, Sport, Spider group before selecting a tire. Once the body style and wheel diameter are verified, the choice becomes much clearer: stay with the period-style bias-ply size or compare the radial size used for that same configuration.
What size rim does a 1968 Fiat 850 use?
The 1968 Fiat 850 uses either a 12-inch or 13-inch rim depending on the sub-model. Coupe, Sport, and Spider applications use the 13-inch tire group, while the Sedan uses the 12-inch tire group. That split is built directly into the tire sizes used on this car.
Checking the actual wheel diameter on the car is essential, especially if the Fiat has been changed over the years. A 12-inch tire cannot be mounted on a 13-inch wheel, and a 13-inch tire cannot be mounted on a 12-inch wheel, so wheel confirmation comes before any discussion of construction, sidewall style, or brand.
Why does the 1968 Fiat 850 have more than one tire size?
The 1968 Fiat 850 has more than one tire size because its covered sub-models do not all share the same wheel-and-tire setup. Coupe, Sport, and Spider models use 13-inch fitments, while the Sedan uses 12-inch fitments. Each group also has both a bias-ply size and a radial size associated with it.
That means tire selection is tied to both body style and wheel diameter, not just the model name. Many vintage cars have been modified or fitted with replacement wheels over time, so it is smart to confirm the sub-model, measure the wheel, and then choose within the correct size family rather than assuming every Fiat 850 uses the same tire.
Bias-Ply & Radial Options
Is 560-13 a bias-ply or radial tire for the 1968 Fiat 850?
560-13 is a bias-ply tire size for the 1968 Fiat 850 Coupe, Sport, and Spider group. It uses the older numeric sizing system, where 5.60 represents the nominal section width in inches and 13 identifies the wheel diameter. Its radial counterpart in this fitment family is 155R13.
Choosing 560-13 usually points toward a more traditional visual presentation and a period-style construction. Moving away from it toward a radial alternative changes more than the sidewall wording, so the wheel width, clearance, and overall stance should be checked carefully before treating the radial option as the better match for your particular car.
What radial tire sizes are equivalent to 560-13?
Radial equivalents for 560-13 include 155R13, P155/75R13, and P155/70R13. In that group, 155R13 is the 80-series metric radial equivalent, P155/75R13 is the 75-series P-metric radial equivalent, and P155/70R13 is the 70-series P-metric radial equivalent. No bias-look radial equivalent is tied to 560-13 here.
These sizes give a useful range of radial alternatives, but they should still be checked against the actual wheel and the car's available space. A recommended rim-width range of 4 to 5 inches is associated with this equivalent family, and it remains important to verify wheel compatibility and body clearance before making a conversion.
What should I check before converting my 1968 Fiat 850 from bias-ply to radial tires?
Start by confirming the Fiat's exact sub-model, wheel diameter, and current tire size family before making any change. On the 1968 Fiat 850, Sedan fitments differ from Coupe, Sport, and Spider fitments, and the available radial alternatives are tied to those separate 12-inch and 13-inch groups rather than to the model name alone.
Next, inspect the wheel width, compare the radial size being considered, and look closely at steering and fender clearance with the suspension at normal ride height. Tire age, wheel condition, and any past modifications also matter, because an older collector car may no longer be sitting on its original wheels or stance.
Choosing the Right Tire
What should I consider when choosing a 560-13 tire for a 1968 Fiat 850?
A 560-13 tire for a 1968 Fiat 850 should be chosen first by confirming that the car is a Coupe, Sport, or Spider with the 13-inch bias-ply fitment. From there, the main variables are brand, sidewall style, tire series, and wheel compatibility, since available options include both BFGoodrich and Firestone classic bias-ply products.
Appearance plays a major role in this size because narrow whitewall and wide whitewall choices are available, and each gives the car a different period-style look. It also helps to compare the tire's rim-width specification against the actual wheel so the selected tire suits both the Fiat's visual goal and its mechanical setup.
What sidewall styles are available for 1968 Fiat 850 tires?
Sidewall style depends on the size and construction being considered. The 155R13 radial choices are blackwall tires, while the 560-13 bias-ply options include narrow whitewall and wide whitewall versions. That gives the 1968 Fiat 850 a clear difference in appearance depending on whether the car stays with a bias-ply presentation or moves to a radial blackwall look.
The best sidewall choice usually comes down to the personality of the specific car and the owner's restoration goals rather than a universal rule. A Coupe, Sport, or Spider set up for a traditional look may lean toward one of the whitewall bias-ply options, while a more understated road-use presentation may point toward a blackwall radial.
What brands offer tires for the 1968 Fiat 850?
Available brands for the 1968 Fiat 850 include Michelin, Dunlop, BFGoodrich, and Firestone. Michelin and Dunlop appear in the 155R13 radial fitment, while BFGoodrich and Firestone appear in the 560-13 bias-ply fitment. Those brand differences also line up with meaningful differences in construction, series, and sidewall presentation.
The right comparison is not simply brand against brand, but brand within the correct size and tire type for the car's setup. Once the wheel diameter and sub-model are confirmed, compare the available series, sidewall style, and rim-width specifications so the selected tire matches the Fiat's intended use and visual direction.
Restoration & Appearance
Which tire should I choose for a period-style 1968 Fiat 850?
A period-style 1968 Fiat 850 usually starts with the correct bias-ply family for the car's body style and wheel diameter: 560-13 for Coupe, Sport, and Spider models or 5.50-12 for the Sedan. Those sizes preserve the vintage sizing format and construction style that suit the character of a late-1960s small Fiat.
From there, the right choice depends on how strictly the car is being restored and what visual presentation you want. Exact originality questions are best settled with marque-specific references, but for many owners the practical goal is selecting the proper bias-ply size first and then choosing the sidewall treatment that best complements the car.
How does tire construction affect the appearance of a restored 1968 Fiat 850?
Tire construction changes the look of a restored 1968 Fiat 850 because bias-ply and radial tires present the car differently even when they occupy the same general fitment family. On this model, the 13-inch Coupe, Sport, and Spider group can be viewed through either 560-13 bias-ply or 155R13 radial sizing, and the Sedan has its own 12-inch bias-ply and radial pair.
A bias-ply choice tends to support a more traditional period-style appearance, especially when paired with available whitewall treatments. A radial can be the better path for owners who prefer that construction, but its look and sizing language are different enough that restoration-minded buyers should consider the visual effect as carefully as the fitment itself.
Fitment, Maintenance & Road Use
Can modifications affect tire fitment on a 1968 Fiat 850?
Yes, modifications can affect tire fitment on a 1968 Fiat 850, especially because this car already has separate 12-inch and 13-inch fitment families depending on sub-model. Aftermarket wheels, suspension changes, ride-height adjustments, or body alterations can all change the amount of room available around the tire and wheel assembly.
That matters even more on a compact vintage car, where clearance margins can be tighter than many modern owners expect. A Fiat 850 with changed wheels or altered stance should have its wheel diameter, wheel width, and steering clearance checked before assuming that a stock-type size or radial equivalent will behave the same way.
What should I inspect before driving a 1968 Fiat 850 on new tires?
Before driving a 1968 Fiat 850 on new tires, inspect the wheels for condition and correct diameter, confirm that the tires match the car's actual sub-model setup, and make sure there is no visible interference at the fenders or steering components. It also helps to verify that each tire is seated properly and holding pressure consistently.
A short, careful road test is a smart follow-up on any collector car, especially one that may have older suspension parts or long periods of storage behind it. Watch for rubbing, vibration, pulling, or uneven stance, and recheck tire pressure after the initial drive so the new installation starts on solid footing.
How should 560-13 tires on a collector 1968 Fiat 850 be maintained?
560-13 tires on a collector 1968 Fiat 850 should be maintained with regular pressure checks, periodic visual inspections, and careful storage habits. Look at the tread and sidewalls for cracking, cuts, bulges, or irregular wear, and pay attention to any tire that loses air between drives. Those checks matter because collector cars often spend more time parked than driven.
Storage conditions make a real difference over time, so keep the car away from prolonged heat, direct sunlight, excess moisture, and ozone sources when possible. Even a lightly used tire should be inspected before road use, since age and inactivity can affect condition just as much as mileage on a small vintage car.
