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Michelin PSS vs Firestone Indy 500 - Track Review

A couple of weeks ago, I posted my first impressions of Michelin's PSS vs Firestone Firehawk Indy 500 tires. I've run PSS's for several years on the Boss, but I'm trying the Indy 500's for the first time. In short, I was worried about the narrower tires (I was running 285/35/18 PSS but could only find the Indy 500 in 275/35/18) and tread squirm, but I was happy with them up to that point just driving on the street. I had the chance to drive on them for three track days now. So what were they like? After my first session, they made an impression that basically persisted for the rest of track sessions on them. Phenomenal, unmatched value. Now, if value is something that stands out above all else, it typically means the compromise between qualities you want and those you don't is less than ideal, but the value is attractive. This is no different. I'll start with the bad, which really boil down to two: ultimate grip and grip longevity.

Grip is noticeably lower than the PSS's. Not by a huge amount, but you can't miss the difference. I think this is more a testament to Michelin's technology rather than a detriment to the Indy 500's. They are second only to PSS's as far as tires I have tried. I haven't tried a whole lot of summer street tires (non R comp), but my experience on track so far includes:
  1. Pirelli P Zero 
  2. Continental ExtremeContact DW
  3. Michelin PSS
  4. BF Goodrich Sport Comp 2
  5. These Firestone Firehawk Indy 500's
I unfortunately don't have objective results (lap times, more on that in a bit) between all except the PSS and the Indy 500's. But subjectively, the Firestones are second only to the PSS. And I would bet serious money they are objectively better than the P Zeros (seriously, someone please take that bet so I can get rich). P Zeros are easily at the bottom. Stone dead last. Don't buy them. They came as OEM tires on the Boss 302 and every Boss 302 owner at the track agrees and have switched to PSS. 

Continental EC DW are really tough to place. They are certainly lower than the PSS, but I'm not so sure about the Indy 500's. See, the trouble with the Continentals is that they feel like a fairly soft tire (structurally). They don't feel sharp and response is relatively slow, so they feel slow, but they actually aren't as bad as they feel. It's tough to say for sure, but I would place them lower than the Indy 500's.

Sport Comp 2 are closer so it's not as easy to say, but Tire Rack actually did a Tire Test when the Indy 500's came out to compare and the Indy 500 beat the Sport Comp 2 in almost every test (albeit by narrow margins sometimes); wet and dry slalom, wet and dry lap time, and wet and dry grip. Only area the Sport Comp 2 were better was braking. You can read the full Tire Rack test here.

That brings it back to the Indy 500's vs the PSS's. Are you willing to live with lower ultimate grip? Be prepared to live with shorter track sessions too, unless you dial down to 7-8/10th for more of the session. The ultimate grip, which is lower than the PSS to start with, doesn't last for long. Maybe 3 hot laps. After that, they seem to settle in a spot for a good while and maintain their grip there, but they won't recover. I tried taking a cool down lap or two, and they still didn't recover. You'll have to come off the track and wait for them to cool a little or slow down the pace. Objective numbers back this up and here is an example session:

Session #1

Lap 1: out lap
Lap 2: 1:21.83
Lap 3: 1:21.45
Lap 4: 1:22.89 - greasy
Lap 5: cool down lap and went in the pits for 5 minutes to check pressure
> Session #1 (after 5 min cool down)
Lap 6: 1:21.50
Lap 7: 1:21.46
Lap 8: 1:22.39 - greasy
Lap 9: 1:23.87 (traffic)
Lap 10: 1:22.33 - greasy
Lap 11: in-lap

So I got two hot laps, then they got greasy. I cooled down for 5 minutes, went back out, got another two good laps and then they got greasy. I could typically get 5 or 6 hot laps from the PSS's before they got greasy enough to be noticeable. Another example session:

Session #2

Lap 1: out lap
Lap 2: 1:21.78
Lap 3: 1:24.40 (traffic)
Lap 4: 1:24.56 (traffic)
Lap 5: 1:22.54 - greasy
Lap 6: 1:22.25 - greasy
Lap 7: 1:23.15 - really greasy
Lap 8: in-lap

I have two other sessions with lap times, one with a best of 1:21.60 and another with a 1:21.50. What do all sessions have in common? A 1:21.xx time is always in lap 2 or 3 (or a cool down period) and not a single session with sub 1:22 lap time after Lap 3. Now, how do those compare to the PSS? Well, my best on the PSS has been 1:20.40, so over 1 second quicker -1.05 quicker to be exact. That's your ultimate grip advantage. With PSS's, I have multiple sessions with a 1:20.xx lap time in laps 4 and/or 5. You won't get the best out of the Indy 500's after lap 3. And they'll let you know they've let go, because they squeal like a pig. When I came off the track after one of the sessions, someone asked me: "Where you the one squealing tires everywhere?" The PSS are good and certainly let you know when they start to let go, but not like this. These tires are LOUD at the limit.

By this point, you're probably thinking I'm trying to paint a grim picture here but, actually, I'm not. Not at all. Here is the thing. Does this car put food on the table by racing? No. Does this car even compete? No. Does this car need to get pushed to 10/10th every single lap? No. Ask yourself those questions. If you answered no to every one, you don't really need the extra little bit of grip and that one second gap. The only other question is: are you ok just having fun at 7 or 8/10th and getting passed a few extra times every session, or do you need to pass as many people as you can? It may seem like a question of ego, but everyone into high performance driving is very competitive. If you answered yes to that last question, I don't think there is a reason to get the Michelin's over these Firestones just because of the ultimate grip and how long it lasts. There is another benefit too.

Anyone who's had PSS on a heavy car (3,600+ lb) knows the struggle: shoulder wear. PSS tires roll over too much when pushed on heavy cars. They eat the shoulders long before centre tread is worn. You need consistent rotation and a lot of camber to get decent life out of them. That has been my experience and a couple of other Boss 302's and E92 M3's I've seen. So far, those Indy 500's seem to be holding much better, despite being narrower (275 vs 285). There are a few reasons, I think:

1. PSS have fairly square tread, so I imagine they "tip" over the edge of tread more easily at high load and roll over the shoulders. The Indy 500's tread is quite curved where it meets the shoulder, so it kind of rolls on the outer tread before it goes on the shoulder.

2. Slightly shorter tire wall height. I was running 285/35/18 PSS and now I'm on 275/35/18 so, with the same aspect ratio and narrower section, tire wall is shorter and should be stiffer - all else being equal.

3. The narrower size (i.e. 275 vs 285) is probably better supported by the wheels since I didn't change the wheels from the TSW Nurburgring 18 x 9.5", which is too narrow for a 285 section tire on track.

4. Finally - and contrary to a lot of online reviews of Indy 500 tires - I think the sidewall structure is stiffer than the Michelin's. I don't know if I'm out to lunch, but when I grabbed an uninflated Indy 500 tire, the sidewall was more resistant to bending. It felt stiffer than uninflated PSS tires. I've seen a lot of people say the PSS have sharper steering response and blame that on softer sidewalls on the Indy 500's. I agree with the sharper response from the PSS, but I think that's actually because of the first point - the square tread. Because the Indy 500 have more curved tread at the shoulder, the bit of "roll" probably dulls steering response vs the PSS's, which are more flat on the road.

Whatever the reason, they wear better than the Michelin's and they feel a little more stable under heavy cornering without the amount of roll over the tire shoulder that the PSS's do so that is a big benefit. And when you consider that the difference in performance is about 1 second and a couple fewer hot laps, you have to ask yourself: is this half the tire? The answer is a resounding no. It is far from it. This tire takes the abuse better, it lasts longer (on the street and on the track, I assume), it is better in the wet, can't tell any difference in ride quality or noise in a car like the Boss 302, and is darn near as quick on track. For literally about half the cost. I kept repeating this at the track whenever someone asked me what I think of them: it's 80% the tire for 50% the cost, and it lasts longer. How can you argue with that?

Now, before you go pull the trigger, there is something worth noting.. my car understeered a lot more on those tires than the PSS's on the third track day, which is when I pushed and got some lap times. I'm not sure why. It was extremely frustrating.. you know the noise of understeer, the howl of disappointment that is as maddening to track rats as a dog whistle is to a dog. My only explanation at the time was that, because they're more sensitive to heat soak, the fronts got hotter and more greasy than the backs in the middle of tight turns, resulting in them letting go sooner than usual. There's no way to tell in real time because the Boss 302 doesn't have tire pressure readouts (not that anyone should be looking at that). By the time I came off the track, hot tire pressure was always equal all around, which is what I aim for, so I can't confirm. Later when I got home, however, I found out that my rear brake pads were basically all gone. A day later, they were metal on metal. To me, that suggested that the front brakes - which already do most of the work - had to do nearly all the work to slow the car down, so the front tires had to use a bit more of grip budget than usual to slow the car down, and less than usual was usable for turning. I really hope that theory is right because it would be darn near hard to fault those tires if that's the case. I'll have to confirm the next time I get back out there with new rear brakes.

For now, all I can say is this: if you plan to go to the track and just have fun at 7-8/10th or under, save your money.. I don't see a reason to buy any tire that's more expensive than those. In fact, you may actually have grip last longer than me. Our track - Atlantic Motorsport Park - is relatively short and technical, with 11 turns in 1.6 miles so it is very hard on tires and brakes. For reference, VIR is 17 turns in 3.3 miles; more than double the length with only about 50% more turns. Big willow is 7 turns in 2.5 miles. Laguna Seca is 11 turns in 2.2 miles. You get the picture. If you don't get paid to lay down qualifying lap times, this tire is darn near hard to beat. If you do, you're running R-comps or slicks, so there isn't even a discussion about street tires.