What were the lap times new and used? I've heard people complain about them cycling out, but its good to see actual data.
Photograph by RJM Media, J.G. Pasterjak (insert)
A question often asked: How will these tires work when they’re worn the heck out?
We have some data to share.
We’ve been running the same set of Vitour P1 tires on our BMW 435i project since April. Since then, they’ve seen more than a dozen heat cycles thanks to track time at the Florida International Rally & Motorsport Park, Daytona and Pitt Race–and the last track on that list wore down our Vitours to the point where there’s almost zero measurably significant tread remaining. At this point, the Vitours practically resemble slicks.
Photograph by J.G. Pasterjak
More recently, those Vitours just ran a Track Attack at the FIRM. While we ran a slightly different configuration this time than we did back when the rubber was fresh in April, we were still able to overlay the VBox data and compare performance in nearly all the corners. We can’t compare lap times, but we can learn a lot from both the subjective feel of the tires and the objective performance in the corners and under braking.
As you’ll see from the data in a moment, the tires still produce some pretty solid ultimate grip–almost indiscernible from new in many cases–but there’s definitely a difference in feel and how that performance is achieved.
Where the fresh tires produced their best laps as early as the first flyer after a short out lap, the thoroughly worn P1s needed a more significant warmup period to produce their best performance. In most cases, we didn’t get our best session on the worn tires until at least our third or fourth lap.
The edge of the envelope was also thinner on the worn rubber. The fresh Vitours gave a lot more leeway for overdriving or mistakes, while the worn versions demanded more precision and gave slightly less usable slip angle.
The difference was noticeable, but not what I’d call dramatic. You just have to sneak up on the edge of adhesion a bit more delicately with the old rubber, while the fresh tires allow you to zoom past it and then dial it back with minimal penalty.
Figure 1
Let’s start with Figure 1 in the FIRM’s Turn 1, but note that the worn tires (red trace) added the shoebox configuration to the preceding straight, meaning a slightly slower and gradual entry. Still, both the new and old tires delivered the same minimal speed. The newer rubber shows a couple of higher lateral g spikes than the old rubber, but the average g through the steady-state portion of the corner was quite similar.
We do see a difference once we start to accelerate out of the corner, though, and that’s going to be a theme here. Once we start loading those old rear tires in more than one direction, we have to make a choice between thrust and side load, because both are compromising each other.
Figure 2
When we get to Figure 2, though, we see some solid performance by the old rubber under braking into Turn 3. The old tire’s red trace practically sits on top of the new tire’s green trace, and the longitudinal acceleration traces look identical as well.
So, if Turn 1 gave us some indication that we might have lost a bit of multitasking ability, braking into Turn 3 is showing us that–at least in the deceleration direction–single-vector performance is still very high on the worn tires.
Figure 3
The most significant difference that we saw on track probably came in the FIRM’s quick Turn 4, a right-hand kink shown in Figure 3. And the difference here was really one of confidence.
Turn 4 demands a decisive turn-in, loading the tires very quickly. The older rubber just didn’t produce the kind of confidence that that turn really wanted, so our entry speed suffered.
The speed trace for the older tires looks remarkably similar to the data generated by OEM cars tested on street rubber, in fact, with a definitive valley in the speed curve. Prepped cars on 200tw rubber tend to produce a trace more like the green one with a faster turn-in and steadier speed through the early part of the corner. The reduced feel just didn’t give me the confidence to attack the entry as hard here.
Figure 4
Figure 4 gives us a nice win for the old tires, though, showing they still have plenty of performance left. The minimum speed though Turn 5 was up a few mph, and the lateral acceleration was also nice and steady, showing some good grip. The old tires also did a good job accelerating off of Turn 5, although the transition area is tight here, meaning less time to fight the multiple demands.
Figure 5
In Figure 5, however, we can see that struggle return in the acceleration off of the FIRM’s hairpin. While both the new and old tires showed comparable grip through the track’s tightest corner, the older tires, both fronts and rears, had some difficulty multitasking.
Once I was able to get everything pointed in the right direction, though, the terminal speed down the ensuing straight was the same for both tires, which is some consolation for the lost speed on the exit.
So, are old Vitours as good as new ones? Well, not quite.
However, the ultimate performance differences are pretty small, and you’re not giving up a ton of potential by running your P1s down to the nub. You are giving up some predictability, though, and you will need to take a bit more time to get some additional heat into the rubber. Keep those factors in mind, and you’ll be rewarded with solid performance right to the end.
Photograph by RJM Media
The recommendation here is to enjoy those Vitours as long as you can. If you have a mission-critical championship event that demands the last thousandth of a second plus the ultimate drivability, newer P1s are certainly the hot setup. But for your typical track weekend or local TT, you aren’t leaving a lot on the table.
These tires, we should add, have only seen a few hundred street miles and were properly stored inside between events. Regular use or more exposed storage will negatively affect track performance as the tires age, so your results could vary.
But as the data shows, age and wear are certainly not the end for Vitour P1s, and with properly preserved examples, you can expect solid track performance until the bitter end.
What were the lap times new and used? I've heard people complain about them cycling out, but its good to see actual data.
theruleslawyer said:What were the lap times new and used? I've heard people complain about them cycling out, but its good to see actual data.
The data from this test was from a track configuration that we'd never run before, which included several hundred feet of additional track. So we couldn't really do a time vs time comparison on a full lap, which is why we broke it down using the common corners.
That said, the delta between fresh tires and the most-worn version we ran on the same track was only a couple tenths of a second (in favor of the freshies). That was about eight weeks and three events prior to this test, though.
I'm still comfortable saying you aren't giving up a ton of time with old P1s, but you are giving up some suppleness and drivability.
And we do have some more new-vs.-old tire info coming–with lap times and, yes, including the Vitour. Look for it later this week.
P1 is my new favorite 200.
Limited time with the P1 so far, but initial impression is that it wears super quick. Perhaps twice as fast the Nankang CRS I had before...
Happy to be corrected if I am wrong.. but I've noticed more than once in previous articles, there is a suggestion that tyres get faster as the tread reduces. Which i never understood. In some way I'm glad this article debunks that theory.
I get that for the same size, same number of heat cycles, a tyre with reduced tread will likely perform better as it will maintain the contact patch better. BUT, in reality, tyre with reduced tread will have been subjected to MORE heat cycles and that drops performance far more than it's gained from reduced tread depth. Am I correct ? This is article agrees at least.
The only exception i can think of is an endurance event. Where there is essentially one (long) heat cycle, so in that case, a tyre with 1 heat cycle and reduced tread MAY perform better than a new tyre with full tread.
T-Money said:Happy to be corrected if I am wrong.. but I've noticed more than once in previous articles, there is a suggestion that tyres get faster as the tread reduces. Which i never understood. In some way I'm glad this article debunks that theory.
I get that for the same size, same number of heat cycles, a tyre with reduced tread will likely perform better as it will maintain the contact patch better. BUT, in reality, tyre with reduced tread will have been subjected to MORE heat cycles and that drops performance far more than it's gained from reduced tread depth. Am I correct ? This is article agrees at least.
The only exception i can think of is an endurance event. Where there is essentially one (long) heat cycle, so in that case, a tyre with 1 heat cycle and reduced tread MAY perform better than a new tyre with full tread.
Well you can have tires shaved. I think its throwing a ton of money away, but you can get a brand new tire at ideal depth. Some tires really fall off a cliff with heat cycles though. Others have a more gradual descent. Seems like the P1 is more the gradual descent type.
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