05RollaXRS

Are you sure your Pilot Sport 4S were extra load rated? The 2020 RCF-Spec PS4S are only SL, which makes only makes sense for street comfort considering RCF needs strong sidewalls due to higher than normal corner loads on the RCF. The sidewalls are significantly stiffer on the extra load as their load rating on XL version of the Sport 4S is much higher with extra reinforcements to handle heavy cornering loads to resist deformation?

RaulTX

Yes, without a doubt. I had been using the XL-rated PS4S's for more than a year before the RCF-spec version even became available. Interestingly, even though the AD08R's definitely have a stiffer sidewall than the XL-rated PS4S's, their load index is lower. The difference must be in the tire compound or some other structural element. It makes you wonder if Lexus' claim that the RCF-spec PS4S is better than the off-the-shelf version is actually true despite their lower load indices.

05RollaXRS

Yes, Lexus claims they are better, but I strongly doubt that. I think the more plausible explanation is, Lexus did not want the ride to become too harsh just like with the OEM Pilot Super Sports as they opted for the lower load index sidewalls to make the car more compliant in street driving conditions. They are still not all that stiff on my XL rated Sport 4S, but definitely compared to the OEM Super Sport, they stay very flat in the very same turns where I used to feel "rolling on sidewalls" effect. Also, there is a nasty speed bump outside my home where I used to notice a little dive when the front tires would land, but now with the XL PS4S, it is very firm and buttoned down when it lands on the other side of the speed bump.

Yri

The AD08R supposedly has steel sidewall inserts, not too sure about the PS4S. To be honest, the AD08R is probably not going to last as long on the track since its more of a performance based tire. It might hold up well, but the wear is probably going to be tremendous after a couple track days (but who knows). The PS4S is definitely a street tire, and I like that but its not a track day tire from what I think.


EDIT: somebody said they got 15k street miles out of their AD08R's, then another guy said he got only 13 months of life out of his AD08R's (he said he only used them on the street). Thats actually quite bad. The Pilot Sport 4S is supposed to last twice that at 30,000 street miles.

05RollaXRS

The 30,000 miles is actually with rotation. Since RCF has staggered setup, you cannot rotate front to back. The rear tires go first (my rears were more bald than the fronts) so it is around 15,000 miles on RCF you can hope for.

Yri

Dang. So I guess the Yokohamas aren't that horrendous when it comes to tire life

BossMoss

Just ordered a set of XL rated PS4S shoes for my RCF today.

05RollaXRS

Good stuff. Now that the tires have broken in, they keep getting better and better. Really love these tires.

05RollaXRS

Update: For the first time since I had these tires, I drove them in nearly 40 C (100 F) temperatures for the first time because of the extremely hot summer this year. Up until now, the hottest I drove them in was 28 - 29 C (84 F) so the 40 C gave me a very unique perspective on how these tires perform at such extremely hot temperatures. That 10 C makes a BIG difference in how these tires perform. I mean, WOW! These tires are unreal. I wanted to make sure I can share it with everyone else. At 40 C, these tires are SO STIFF. You feel every little bump and imperfection in the road, but man do they feel sporty. Mine are XL so I am not sure if the SL behave the same way.

Even cornering at crazy speeds, the car has a very flat attitude with very sharp on-center steering response and I never could break traction (which is very easy to do when the temperatures are mild). With my SprintBooster set to race mode level 5, I could not break traction off the line. That was surprising considering how easy it is to break traction in milder temperatures. These were literally like slick racing tires. No exaggeration. In the turns, I would back off before I felt the front end or the back end beginning to break away a bit because there was so much traction with almost no roll that I felt car would snap without any warnings, but I am sure the tires had more left. Also, the brakes are very "grabby" due to the tire.

All in all, Michelin made these tires to run very hot. That is why they began to really make sense as track-oriented tires at such hot temperatures. Looks like the hotter the temperature, the more these tires like it. They felt like racing slick tires. These tires made the car so much more fun in spirited driving.

Aversed

After reading this thread, got the PS4S as my replacement for the stock PSSs. A pretty penny, but really excited to try them out.

Going to look into suspension upgrades also so I can prolong the life of these. Rotation side to side should also help a bit.

Yri

The stock PSS tires come at a pretty penny anyhow. If you want to prolong the life of your tires, especially the front ones, look into getting the RR Racing LCA bushing, helps a lot with dynamic toe issues. Also, did you get the XL rated PS4S or the SL, since the XL has a stiffer sidewall as Rolla said. Stiffer sidewalls mean less roll, and too much roll is bad for a tire when it is under load.

Aversed

Yup! Got the XL rated PS4s.

The LCA bushings was one of the first things I looked into after buying my tires. I'm on stock height and wheels, i should still be able to reap the benefits of the LCA bushing regardless right? I'm looking into getting springs since my car has AVS and I want to retain the functionality of it.

05RollaXRS

You would really like the PS4S. Yes, the bushings really help a lot in terms of steering feel especially over abrupt bumps while the steering is under asymmetric load (tight turning). They will make the ride stiffer as there is less flex in the control arm and steering connect. That is the only suspension mod I will do on my RCF and call it a day. If you are looking into lowering springs, get the swift springs R-spec and stay away from the RSR super downs. Many RCFs have had blown shocks due to the very soft spring rates to achieve an aggressive drop.

Yri

Also, many springs will cause shocks to deteriorate faster just because of the lower spring rate. Remember, with a lower spring rate, the car will become more 'boaty' in a sense. When you are driving a 4,000 pound whale of a car, you want higher spring rates in general. Gives better turn in, far faster direction changing and the like. It may be best not to buy springs for that reason, though you do achieve the benefit of a lower center of gravity. Also, probably not going to reply too much on this spring/suspension topic because I don't want to thread hijack.

Anyhow, back on topic, PS4S tires are the rubber equivalent to gold.

05RollaXRS

Yep. It is the unfortunaate part of lowering springs. Usually the more lower the drop, the more aggressive the spring rates need to be in order to keep the suspension stroke in control. If you are going through a rough patch, a 1.5 inch lower suspension will have far more compresson/rebound strokes than that other 1.5 inch taller spring/damper setup. The lower suspension simply has to work much harder under demanding conditions/cornering loads just to keep up.

Most of the springs in order to achieve aggressive "slammed" look end up with softer spring rates to get that look. Usually a 1 inch drop is pretty safe compared to OEM. Anything more and one is risking blowing the shocks. I have had some terrible experiences with blown shocks with Tein S-techs so I learned my lesson from that.