How to get fresh, modern tires that retain those period-correct look

[Editor's Note: This article originally appeared in the November 2020 issue of Classic Motorsports.]

Brakes don’t stop the car. Tires do. And the tires on our 1984 Porsche 911 Carrera, we admit, had gotten way too old.

How old? More than a decade.

Tire Rack, one of the biggest retailers among the car enthusiast community, says the lifespan of a tire is six to 10 years. 

Our own testing on a Triumph TR6 a few years back revealed just how much fresh tires matter:  A set of never-used yet 33-year-old Michelins required more than 160 feet to stop from 60 mph, while a brand-new set of Vredestein Sprint Classics only needed 140 feet. And at the same time, the new tires were quieter and exhibited much better handling. We had committed a major faux pas with the Porsche.

Before they aged out, though, our Porsche’s Pirelli P Zero System tires were perfect for the task at hand. First, they delivered sporty performance thanks to a soft 140-treadwear rating as well as A grades for treadwear and traction. Tire Rack places them in the max-performance-summer tire class–perfect for a sports car that doesn’t see any inclement weather.

Second, they simply looked the part, with the retro styling and tread pattern appropriate for an ’80s icon. 

One more thing to love: Porsche N-specification approval. What does that mean? 

Here, we’ll crib from Tire Rack:

“Porsche designs and manufactures some of the highest performance vehicles in the world. Because of the integral role that tires play in vehicle performance, Porsche has integrated tire development throughout their process of vehicle development. To be an Original Equipment tire provider on a Porsche vehicle or be approved by Porsche for the replacement market requires the joint product development efforts of the tire engineers working alongside the Porsche vehicle engineers.”

Despite the soft compound, the Pirellis wore well, too. They come sporting 10/32 inch of tread. Our fronts showed 7/32, with the rears at 6/32. (Okay, maybe we need to drive this one more.) The Pirellis still looked good, too: no cracks, no issues. 

And then we spied the build dates: 2007 for the fronts and 2009 for the rears. Okay, these tires should have been removed from service a while ago. (Do as we say, not as we do, okay?)

So, back to our Porsche: Step one was research. 

Tire Rack didn’t have the rear P Zeros for our application in stock, but all these years later we still had the same goals: sporty performance, appropriate looks and Porsche’s N-rating. 

While we were elbow deep in our research, Yokohama dropped a bit of engaging news: Its A-008P, an ’80s performance icon, was heading stateside in Porsche-specific sizes. They’d carry a UTQG rating of 240 A A.

Game, set, match. 

One thing about the A-008P’s N-rating, though: Its N0 rating doesn’t seem to match the latest spec. Woody Rogers, knower of all tire things at Tire Rack, provides more information on that subject:

Our old Pirellis still sported plenty of tread, but they had simply aged out. A fresh set of tires–in this case, Yokohama’s reintroduced A-008P–allowed our Porsche to retain its ’80s looks while carrying the proper Porsche certification. 

“The N# homologation marking system used on the A-008P is an older, less specific version of the new, going-forward system of NA#, NB#, etc., that ties the homologation to a particular chassis. Porsche realized some years ago that with a growing number of platforms that have some tire size commonality, they needed a more precise designation system to help keep things separate. Their tires are so highly tuned to the platform they felt it was a disservice to go only by the presence of an N-spec number and assume it is the best option for a vehicle. 

“For the A-008P N0 tires, they could never get a NA#-type rating, because it isn’t available in the correct sizes for the new platforms that benefit from the new system. Porsche rolled out the clarified rating starting with the 992 (911) platform last year and will use it for all new homologations going forward.”

We also had to consider the available sizes for the A-008P. We’d been running the OE sizes for our Porsche, meaning 205/55ZR16 fronts along with 225/50ZR16 rears. Yokohama only offers the A-008P in two sizes aimed at the Porsche 911 Turbo: 205/55ZR16 and 245/45ZR16. Would the wider rears be an issue?

We did the numbers, all easily found online. The 225/50ZR16 Pirellis have a 25.1-inch outside diameter and a 9.3-inch section width. The 245/45ZR16 Yokohama sports a 24.6-inch outside diameter and a 9.6-inch section width. We figured that the slight reduction in overall diameter would, if anything, quicken acceleration a tad. Besides, there’s plenty of room inside those rear fenders to accommodate the increased width. 

Our car is also running 16x7-inch front wheels and 16x8-inch rears. Yokohama shows those sizes to be well within the range for the A-008P. 

So we ordered the new retro Yokohamas. A set of four retail for about $860–with free shipping from Tire Rack. Our Pirellis retailed for $640 when we installed them, but that was before shipping. 

Initial impressions of the new Yokohamas? First, yes, the ride is much better on fresh tires, as they no longer seem to crash from bump to bump. Steering feels responsive, yet at the same time, these tires don’t seem to overpower the chassis. They feel like an appropriate fit for an ’80s sports car that has roots back in the ’60s.

And then there are the looks. Perfect. We’re back to the glory days of IMSA GTP, “Miami Vice” and big hair. 

Tire Testing: Braking Numbers Tell The Full Story

We didn’t simply install the new tires and drive around. We wanted to show how they compared to the old ones. While we realize this isn’t a strict apples-to-apples comparison, it demonstrates the difference between new tires and ones that look good but have aged out.

Our testing focused on one simple metric: 60-to-zero braking. Data was captured via an APEXPro, an acquisition system that uses both GPS and inertia measurements. Testing was done on two separate days, but the conditions were nearly identical: sunny, ambient temperatures in the 60s, and all on the same stretch of pavement. Before testing the Yokohamas, we put about 60 miles on them in order to remove any mold release compound. Our own J.G. Pasterjak handled the driving, and here we’ll let him take over for the rest of the story:

First, I’d like to stress that while the data trace is fairly obvious, it doesn’t convey the full feel of the difference in these two tires. While the old Pirellis felt reasonably grippy when driven under the limit, their at-limit and over-limit performance was very poor and, possibly even worse, very unrecoverable. 

Once you lock the old tires, you have to come quite far out of the brakes to get them to start rotating again. I think this bears mentioning for anyone who thinks their old tires still feel fairly grippy: They may feel decent up to about 90% of their capacity, but that last 10% is what makes the real difference between an insurance claim and merely soiled pants. 

So, let’s look at these stops on the data traces. The red trace shows the data for the old tires, while the blue trace depicts the new Yokohamas. Each trace shows one representative stop, and they have been slightly offset to make them easier to read. While the full stop on the old tires looks like it went some 15 meters longer, when you line up the initial brake application points, it’s actually more like an 8-meter difference: 60 meters for the old tires versus 52 meters for the new ones.

The first thing we notice is how much steeper and more aggressive the initial application of the braking force is with the new tires. The old ones must be loaded more gradually, as shown by the rounder and shallower initial part of the speed curve. Those first few miles per hour needed to come off slowly while we found the ideal pedal pressure to avoid terminal lockup.

We also see the main part of the speed trace for the Yokohamas dropping more steeply than the Pirelli trace. This shows us losing speed at a faster rate with the newer tires. 

At around 35 mph, we see the Pirelli trace flatten out completely for a moment as the right-front tire locked up, forcing us to get out of the brakes and then back in to continue the braking exercise. 

Conversely, while the Yokohama trace has many tiny changes in deceleration rate due to threshold braking, we never see a point on the curve where the car stops decelerating at an aggressive rate.

Toward the bottom of the curve, we were doing some serious modulation with the old tires to keep them from terminal lockup. That’s the sawtooth part of the trace toward the bottom. 

Except for one small hiccup at the bottom of the Yokohama trace, which was not a lockup but more likely just road undulation, the Yokohama curve just continues downward to a stop.

Even the stops themselves are different. The Yokohamas came to a full and complete stop in one motion, while we had to “chauffeur stop” the old tires at the last second by bleeding off some braking force to keep them from sliding to a stop.

And while we’ve offset these curves from each other slightly for reading clarification, we can still see a distance advantage in the newer tires. The Yokohamas came to a full stop almost 10 meters shorter than the old tires. And while the distance is great–you can fit a lot of kids on bikes in 10 meters, nearly 33 feet–the even bigger story is the lack of drama the new tires displayed while they did their job.

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