In 1999 Porsche balanced tradition and transition, with the 911 carrying the brand’s rear-engine performance legacy while the Boxster broadened the lineup with a lighter mid-engine roadster. Both models belong to the modern water-cooled era, but they do not all use the same tire package across the range. Across 1999 Porsche models there are six tire sizes, with four shared between the 911 and Boxster and two additional 16-inch sizes used only on the Boxster. The key first step is to confirm whether your car is a 911 or Boxster, then verify whether it runs a 16-, 17-, or 18-inch wheel package before narrowing your tire choice.
Which Tire Size Is Right for Your 1999 Porsche
Six tire sizes are used across 1999 Porsche vehicles, and fitment varies by model rather than staying universal across the full range. Every size here is a radial, so the real choice starts with confirming whether your car uses 16-, 17-, or 18-inch wheels and then matching the correct front or rear size. Understanding that distinction before choosing a product saves time and helps ensure the right match.
Year(s): 1999|Fit(s): 911, Boxster|Construction: Radial|Rim: 17 in
205/50R17 is a metric radial with a 205-millimeter section width, a 50-series aspect ratio, and a 17-inch rim diameter. This size is available from BFGoodrich and American Classic, with blackwall and wide whitewall sidewall styles; speed ratings vary by product, including W-rated options to 168 mph. Because it fits both the 911 and Boxster, this is one of the shared 17-inch sizes across the 1999 Porsche range. It suits owners who need the correct modern metric format for a shared front or rear application while still having a choice between contemporary blackwall styling and a more custom-oriented whitewall look.
Year(s): 1999|Fit(s): 911, Boxster|Construction: Radial|Rim: 17 in
255/40R17 is a metric radial with a 255-millimeter section width, a 40-series aspect ratio, and a 17-inch rim diameter. This size is available from BFGoodrich, Nitto, and Vredestein in blackwall form, and speed ratings vary by product, with W-rated tires to 168 mph and Y-rated tires to 186 mph. Because it fits both the 911 and Boxster, it is a shared 17-inch size rather than a model-specific one. It is the wider companion size in a staggered setup and is the right place to focus if your 1999 Porsche uses a 17-inch rear fitment.
Year(s): 1999|Fit(s): 911, Boxster|Construction: Radial|Rim: 18 in
225/40R18 is a metric radial with a 225-millimeter section width, a 40-series aspect ratio, and an 18-inch rim diameter. This size is available from BFGoodrich and Nitto in blackwall form, and current options in this size carry W speed ratings to 168 mph. Because it fits both the 911 and Boxster, it serves as one of the shared 18-inch sizes across the year and make. It is typically the narrower half of an 18-inch staggered package, so owners should confirm that their car is using the 18-inch wheel set before selecting it.
Year(s): 1999|Fit(s): 911, Boxster|Construction: Radial|Rim: 18 in
265/35R18 is a metric radial with a 265-millimeter section width, a 35-series aspect ratio, and an 18-inch rim diameter. This size is available from BFGoodrich and Nitto in blackwall form, with speed ratings that vary by product from W to 168 mph up to Y to 186 mph. Because it fits both the 911 and Boxster, it is another shared size rather than one limited to a single model. It is the broader 18-inch fitment and is the size to confirm when your 1999 Porsche uses the wider rear portion of an 18-inch staggered setup.
Year(s): 1999|Fit(s): Boxster|Construction: Radial|Rim: 16 in
205/55R16 is a metric radial with a 205-millimeter section width, a 55-series aspect ratio, and a 16-inch rim diameter. This Boxster-specific size is available from BFGoodrich and Michelin in blackwall form, and speed ratings vary by product with W-rated tires to 168 mph and Y-rated tires to 186 mph; tube status also varies by product, with Michelin marked TL. It is not universal across 1999 Porsche models, so it should be chosen only for Boxsters equipped with the 16-inch wheel package. This size makes the most sense for owners preserving the stock 16-inch setup rather than moving into one of the larger-diameter combinations used elsewhere in the range.
Year(s): 1999|Fit(s): Boxster|Construction: Radial|Rim: 16 in
225/50R16 is a metric radial with a 225-millimeter section width, a 50-series aspect ratio, and a 16-inch rim diameter. This Boxster-specific size is available from BFGoodrich and Michelin in blackwall form, and speed ratings vary by product with W-rated tires to 168 mph and Y-rated tires to 186 mph; tube status also varies by product, with Michelin marked TL. It is specific to Boxster models using the 16-inch package rather than the shared 17- or 18-inch Porsche sizes. It is the wider companion to 205/55R16, so it is the size to confirm when matching the rear portion of a 16-inch Boxster setup.
Two models are covered for 1999 Porsche. Tire size does vary by model, because the 911 shares four 17- and 18-inch sizes with the Boxster while the Boxster also uses an additional 16-inch pair. Select a model below to narrow the fitment history and see the tire options that match that specific Porsche.
1999 Porsche 911
The 1999 Porsche 911 belongs to the early 996 generation, the first water-cooled 911 and a major turning point in the model’s long-running evolution. Its tire fitments here mount on 17-inch or 18-inch wheels, reflecting the car’s move into a more modern high-performance tire era while still preserving the familiar staggered Porsche approach.
The 1999 Porsche Boxster was Porsche’s mid-engine sports car aimed at open-top balance and everyday usability, and it quickly became a defining model for the brand’s modern revival. Its tire fitments span 16-inch, 17-inch, and 18-inch wheel packages, so Boxster owners need to verify wheel diameter before choosing a replacement set.
Twenty-five products are available across six tire sizes for 1999 Porsche vehicles. The shared 17- and 18-inch sizes span BFGoodrich, Nitto, Vredestein, and American Classic, while the Boxster-only 16-inch sizes are available from BFGoodrich and Michelin; sidewall styles range from blackwall to wide whitewall. Confirm wheel diameter first, and check the individual tire’s speed rating and tube marking where they vary within a size.
These answers focus on how 1999 Porsche tire fitment changes between 911 and Boxster models, how the 16-, 17-, and 18-inch sizes relate to each other, and what sidewall, speed-rating, and collector-care details matter before putting miles on the car.
Size Basics & Fitment
What tire sizes fit 1999 Porsche vehicles?
1999 Porsche vehicles use six tire sizes across the 911 and Boxster range: 205/50R17, 255/40R17, 225/40R18, 265/35R18, 205/55R16, and 225/50R16. The 911 uses the four shared 17- and 18-inch sizes, while the Boxster uses those same four plus the 16-inch pair of 205/55R16 and 225/50R16. Rim diameters therefore span 16, 17, and 18 inches, and rim width ranges vary by size from 5.5-7.5 inches on the narrower sizes up to 9.0-10.5 inches on 265/35R18.
The practical takeaway is that year and make alone are not enough for a 1999 Porsche. You need to identify whether the car is a 911 or Boxster and then confirm the actual wheel package on the car, especially if wheels may have been changed over the years. Once wheel diameter is confirmed, the correct front and rear size pair becomes much easier to sort out.
What does 205/50R17 mean on a 1999 Porsche tire?
On a 1999 Porsche, 205/50R17 is a metric radial size. The 205 is the nominal section width in millimeters, 50 is the aspect ratio, meaning the sidewall height is 50 percent of the section width, R indicates radial construction, and 17 is the wheel diameter in inches. For 1999 Porsche fitment, this size appears on both the 911 and Boxster and uses a rim width range of 5.5 to 7.5 inches where that specification is supplied.
That code matters because it tells you both the tire’s physical format and the wheel diameter it must fit. A 205/50R17 cannot be mounted on a 16-inch or 18-inch wheel, even if the car is the same year and make. On a 1999 Porsche, the code is especially useful when sorting a shared size that can belong to more than one model depending on the wheel package installed.
Do all 1999 Porsche models use the same tire size?
No. The 1999 Porsche 911 and 1999 Porsche Boxster share four sizes—205/50R17, 255/40R17, 225/40R18, and 265/35R18—but the Boxster also uses 205/55R16 and 225/50R16. That means the 911 stays within 17-inch and 18-inch fitments here, while the Boxster spans 16-inch, 17-inch, and 18-inch applications depending on wheel package.
For a buyer, that means the model name matters just as much as the year. A Boxster owner with the base 16-inch setup should not assume a shared 17-inch or 18-inch Porsche size applies, and a 911 owner should not default to the Boxster’s 16-inch pair. Confirm the model first, then verify the wheel diameter and whether the car uses a staggered front-and-rear combination.
Buying the Right Tire
What sidewall styles are available for 1999 Porsche tires?
Most 1999 Porsche tire sizes here are available in blackwall form, which aligns with the period-correct performance look buyers usually expect on a late-1990s Porsche. One exception is 205/50R17, which is also available with a 0.875-inch whitewall through American Classic. The remaining shared sizes—255/40R17, 225/40R18, and 265/35R18—as well as the Boxster-only 16-inch sizes, stay within blackwall offerings.
If originality and factory appearance are the goal, blackwall is the natural choice for a 1999 Porsche 911 or Boxster. The whitewall 205/50R17 option is more of a specialty styling direction than a typical Porsche restoration choice. That makes sidewall style a useful filter once you have already confirmed the correct size, especially for an owner balancing period appearance with a personalized presentation.
What brands make tires for 1999 Porsche vehicles?
1999 Porsche tire sizes are available from BFGoodrich, Nitto, Vredestein, Michelin, and American Classic. BFGoodrich appears across every size family here, Nitto covers the shared wider 17-inch and 18-inch performance sizes, Vredestein appears in 255/40R17, Michelin covers the Boxster’s 16-inch sizes, and American Classic appears in 205/50R17. Brand choice therefore changes somewhat with the wheel package and size your Porsche uses.
That spread gives owners a useful mix of performance-oriented and specialty options within the same year and make. A 16-inch Boxster owner will see a different brand mix than a 17-inch or 18-inch 911 owner, so it helps to think in terms of size first and brand second. Once the correct size is established, brand differences can be weighed by sidewall appearance, speed rating, and intended use.
What is the difference between BFGoodrich and Michelin options for 1999 Porsche 16-inch tires?
On 1999 Porsche Boxster 16-inch sizes, BFGoodrich and Michelin overlap in both 205/55R16 and 225/50R16, but they are not identical in specification detail. The BFGoodrich 205/55R16 products use a 5.5-7.5 inch rim width range and include W-rated versions, while the Michelin SX MXX3 N2 in 205/55R16 is marked 91Y TL. In 225/50R16, BFGoodrich products use a 6.0-8.0 inch rim width range and W speed rating, while the Michelin Pilot Sport carries a 92Y TL marking.
For a Boxster owner, that means the comparison is not just brand preference. Speed rating, tubeless marking, and the character of the tire line itself all deserve a look before deciding. If your car is driven in a way that makes original-style Porsche-spec flavor important, the Michelin choices may stand out, while BFGoodrich gives broader coverage across the 1999 Porsche size range.
Fitting & Setup
What rim width do 1999 Porsche tires require?
Rim width requirements on 1999 Porsche tires vary by size. The 205/50R17 and 205/55R16 sizes use 5.5-7.5 inch rims, 225/50R16 uses 6.0-8.0 inch rims, 225/40R18 uses 7.5-9.0 inch rims, 255/40R17 uses 8.5-10.0 inch rims, and 265/35R18 uses 9.0-10.5 inch rims. Those ranges reflect the fact that front and rear Porsche fitments are not interchangeable just because the tires belong to the same model year.
The important step is to match the tire not only to wheel diameter but also to the actual wheel width on the car. A rear wheel from a staggered 1999 Porsche setup can easily fall outside the acceptable width for a narrower front tire, and the same is true in reverse. Checking the wheel’s stamped or measured width before ordering helps prevent mounting problems and preserves the handling balance Porsche intended.
Do 1999 Porsche tires require inner tubes?
Most 1999 Porsche tire offerings here are radial performance tires without a tube-type marking, and some Michelin options are explicitly marked TL for tubeless use. On the Boxster’s 16-inch sizes, tube status varies by product because Michelin is marked TL while the BFGoodrich products are not described that way in the same size family. The shared 17-inch and 18-inch sizes also do not carry a tube-type marking in the size descriptions shown here.
For a 1999 Porsche, the wheel itself matters just as much as the tire marking. Original late-1990s Porsche road wheels are normally tubeless wheel designs, but the exact tire you choose should still be checked by its sidewall marking and manufacturer guidance before mounting. If there is any doubt about a particular wheel or tire combination, confirm it with the installer before the tires are fitted.
Can the original 1999 Porsche wheels be used with all tire sizes?
No, not across the full 1999 Porsche range. The sizes here are split across 16-inch, 17-inch, and 18-inch wheel diameters, so a tire must match the wheel diameter exactly. A 205/55R16 or 225/50R16 fits only a 16-inch wheel, the 205/50R17 and 255/40R17 pair fit 17-inch wheels, and the 225/40R18 and 265/35R18 pair fit 18-inch wheels.
Original wheels can absolutely be used, but only with the tire sizes intended for that wheel diameter and width. That is especially important on a 1999 Porsche because both the 911 and Boxster often use staggered front and rear combinations. If the car has had aftermarket wheels installed at some point, verify both wheel diameter and width on the car rather than assuming the original factory package is still present.
Maintenance, Storage & Longevity
How should I store a 1999 Porsche when the tires are fitted?
A 1999 Porsche should be stored in a cool, dry, dark space with the tires kept away from direct sunlight, electric motors, welders, battery chargers, and other ozone-producing equipment. Inflate the tires to the correct operating pressure before storage, keep the car off damp ground, and move it periodically if practical so the same section of tread is not carrying the load for months at a time. Radial tires generally tolerate storage better than older bias-ply designs, but they still age when left static in poor conditions.
For a collector-driven 911 or Boxster, tire care during storage matters as much as miles driven. A car that sits for long periods can develop flat spotting, pressure loss, and sidewall aging even when the tread still looks fresh. If the Porsche will be parked for a long season, occasional rolling or properly supporting the vehicle can help reduce stress on the tires without turning storage into a restoration project.
How long do tires on a 1999 Porsche typically last?
On a 1999 Porsche, tire age is usually more important than tire mileage. A sound rule for collector and enthusiast cars is to begin evaluating tires closely once they reach roughly five to seven years of age and to treat around ten years as a serious replacement consideration regardless of remaining tread. The DOT date code on the sidewall is the quickest way to confirm the tire’s age, and high-performance radials can age out even when a low-mile Porsche has been driven sparingly.
That matters because many 1999 Porsche cars live a part-time life: weekend use, climate-controlled storage, and limited annual mileage. Tread depth alone can give a false sense of security on a lightly driven sports car. If the car still carries older tires, inspect them with age in mind rather than waiting for visible wear to make the decision for you.
How often should tires on a 1999 Porsche be inspected?
Tires on a 1999 Porsche should be inspected before every drive and again before any longer outing. Look for cracking, bulges, punctures, irregular wear, and any change in pressure retention, and check both the tread surface and inner sidewall if the wheel design allows a clear view. If your chosen tire is marked tubeless, valve stem condition still deserves attention because a leaking stem can mimic a slow tire failure.
Routine inspection is especially important on a 911 or Boxster because the car’s handling depends heavily on maintaining proper tire condition and matched front-to-rear fitment. A small issue that might go unnoticed on a heavier daily driver can change how a sports car feels at speed or under braking. Make tire checks part of the same pre-drive routine as fluid level, brake feel, and light mechanical inspection.
Restoration & Authenticity
What tires were originally fitted to the 1999 Porsche 911?
A 1999 Porsche 911 originally belonged to a fully modern radial-tire era, so radial construction is the correct starting point for restoration and preservation work. The 911 uses the shared 17-inch and 18-inch metric radial sizes here rather than the Boxster-only 16-inch pair. Michelin appears in Porsche-correct late-1990s sizing on related fitments within this year and make, but original-equipment brand and exact specification can still vary by wheel package and market.
For an owner focused on authenticity, the first goal is to match the correct size and wheel diameter package for the specific 911. After that, details such as speed rating, sidewall appearance, and any Porsche-specific tire line become more important. If the car is being prepared for marque judging, it is wise to confirm factory-delivery fitment through Porsche literature or a knowledgeable Porsche club source before making the final tire choice.
Does correct tire fitment matter for showing a 1999 Porsche?
Yes, correct tire fitment matters on a shown 1999 Porsche because judges and knowledgeable enthusiasts notice whether the wheel diameter, tire size, construction type, and sidewall appearance match the car’s era and intended specification. For a late-1990s Porsche, a modern radial blackwall presentation is the expected visual and technical direction, while an unconventional sidewall treatment such as a whitewall on 205/50R17 changes the appearance immediately. Even when the tire fits physically, an obviously non-period look can affect authenticity.
The level of scrutiny depends on the event. A casual local show may reward cleanliness and presentation, while a marque-focused Porsche event may pay close attention to wheel and tire correctness. If the car is being judged seriously, treat size and sidewall style as part of the restoration plan rather than an afterthought, and compare your setup against event guidance or club knowledge before final installation.
What is the difference between BFGoodrich g-Force and BFGoodrich g-Force Phenom T/A for a 1999 Porsche?
For a 1999 Porsche, BFGoodrich offers more than one performance family in overlapping sizes. In 205/50R17, 225/40R18, 265/35R18, and 205/55R16, the g-Force Phenom T/A appears alongside g-Force Sport Comp-2 or g-Force Comp-2 A/S options, with close but not identical weights and load figures where stated. For example, the 205/50R17 Phenom T/A carries 1,433 pounds at 50 psi, while the Comp-2 A/S in the same size carries 1,279 at 51 psi.
That means the choice is not simply a matter of brand, since both tires come from the same maker. Owners comparing them should look closely at the exact size, the intended use of the car, and any differences in load figure or weight that matter to them. For a 1999 Porsche kept near factory appearance, the deciding factors are usually the tire’s specific line character and its exact specification within the correct size.
Safety & Road Use
Are 1999 Porsche tires safe for highway driving?
Yes, the available 1999 Porsche tires are highway-capable radial tires, and the speed ratings shown here are well above normal U.S. interstate speeds. Depending on size and product, ratings include W to 168 mph and Y to 186 mph. On a 1999 Porsche 911 or Boxster in sound mechanical condition, the car’s overall setup, alignment, suspension health, and tire age are usually more important to real-world highway safety than the raw speed ceiling printed on the sidewall.
The critical point is that speed rating only matters when the tire is in good condition and properly inflated. A fresh W-rated tire and an aged Y-rated tire are not equal from a safety standpoint if the older one has cracking, impact damage, or pressure loss. For highway use, focus on condition, matching sizes front to rear, and the correct wheel package before thinking about the top end of the speed letter.
What inflation pressure should I use for 1999 Porsche tires?
Inflation pressure for a 1999 Porsche should be based first on the car’s factory guidance for its specific wheel and tire package, then checked against the tire maker’s own load-and-pressure limits. Some tires here include load figures such as 1,279 pounds at 51 psi for 205/50R17, 1,653 pounds at 50 or 51 psi for certain 255/40R17 products, 1,389 pounds at 50 or 51 psi for some 225/40R18 products, 1,609 pounds at 50 or 51 psi for some 265/35R18 products, 1,356 or 1,477 pounds at 50 or 51 psi for 205/55R16, and 1,389 pounds at 51 psi for 225/50R16.
Those figures are maximum load-and-pressure references for the tire itself, not a universal inflation recommendation for every 1999 Porsche. Front and rear pressures often differ on Porsche applications, especially with staggered fitments. The safest approach is to start with the Porsche door-jamb or owner’s manual specification for your exact model and wheel package, then use the tire maker’s sidewall information as the tire’s operating limit rather than your automatic target.
What should I check before taking a 1999 Porsche on a longer drive?
Before a longer drive in a 1999 Porsche, inspect each tire for tread depth, sidewall cracking, cuts, bulges, and uneven wear, then confirm cold inflation pressures and the condition of the spare if the car carries one. Check valve stems for age and leakage, and pay close attention to any tire that has been sitting for long periods or has aged out even with low mileage. On staggered setups, verify that the front and rear sizes remain correctly paired.
A tire check should be part of a broader pre-trip lookover on any late-1990s sports car. Brakes, fluids, alignment feel, and suspension condition all influence how the car behaves once speeds rise and road temperatures change. If anything about the tire condition is questionable, address it before the trip rather than relying on the fact that the Porsche drove normally on a short local run.
