First time at Track with the RCF
#16
Lexus Test Driver
Glad to see all the coolers did their job on your RCF and kept the car nice and cool.
32 psi is on the low side. Stock recommended MPSS pressure is 36F/36R cold. I usually go with 36F/38R completely cold. I go 2 psi higher on the rear to get relatively stiffer sidewalls on the back while keep the front a bit softer at 36 psi so that I can feel the front end bite a bit in the turns rather than making it too flat and darty.
These particular RCF-spec MPSS tires themselves are a disappointment as they were not made XL rated with soft sidewalls due to daily drivability. Lexus changed it in 2020 with a specially designed MPS4S tire with added reinforcements into the sidewalls in addition to the XL rating.
Our MPSS roll over and deform too much under hard turning. XL rated MPS4S at least for spirited/track driving or Michelin Pilot Cup 2 for time attacks. I have heard RCF does very well with Michelin Pilot Cup 2 on the track. They grip like Velcro and have very hard sidewalls. They also are much lighter than the stock tires so you lose a few pounds of unsprung weight. Only downside is that they don't wear very long.
32 psi is on the low side. Stock recommended MPSS pressure is 36F/36R cold. I usually go with 36F/38R completely cold. I go 2 psi higher on the rear to get relatively stiffer sidewalls on the back while keep the front a bit softer at 36 psi so that I can feel the front end bite a bit in the turns rather than making it too flat and darty.
These particular RCF-spec MPSS tires themselves are a disappointment as they were not made XL rated with soft sidewalls due to daily drivability. Lexus changed it in 2020 with a specially designed MPS4S tire with added reinforcements into the sidewalls in addition to the XL rating.
Our MPSS roll over and deform too much under hard turning. XL rated MPS4S at least for spirited/track driving or Michelin Pilot Cup 2 for time attacks. I have heard RCF does very well with Michelin Pilot Cup 2 on the track. They grip like Velcro and have very hard sidewalls. They also are much lighter than the stock tires so you lose a few pounds of unsprung weight. Only downside is that they don't wear very long.
Last edited by 05RollaXRS; 05-26-19 at 10:44 AM.
#18
Swapped out to a square setup 275/30/19 Nitto Invio for second day. Not really a track tire lol but my buddy’s shop only had these and it was Saturday afternoon and got the set for 400.00 brand new. Fay two was cooler and tires felt much more stiff lower side wall. Picked up two seconds per lap.
#19
Lexus Test Driver
Well I’m sure the square tires helped a lot.
Plus you had bigger front patch for more grip.
Guessing you ran the psi higher?
275/30/19 is a tad short in the back compare to oem sizing but it’s pretty close.
I’ve ran 275/30 fronts and 275/35 rears before. Car felt good.
Plus you had bigger front patch for more grip.
Guessing you ran the psi higher?
275/30/19 is a tad short in the back compare to oem sizing but it’s pretty close.
I’ve ran 275/30 fronts and 275/35 rears before. Car felt good.
#20
Smaller tire changes the effective final drive making it higher effective gear. The factory 2.937 is now effectively a 3.05. It’s only a 3% increase but that’s what they did on the 2029 which was a 5.5% increase.
Lexus claims an improved 0-60 time of just under 4 seconds thanks to a higher final-drive ratio (3.13 versus 2.97) and a new launch control system. Off-the-line acceleration does feel peppier (even without using launch control),
Lexus claims an improved 0-60 time of just under 4 seconds thanks to a higher final-drive ratio (3.13 versus 2.97) and a new launch control system. Off-the-line acceleration does feel peppier (even without using launch control),
Last edited by Gearbangin; 05-27-19 at 04:00 AM.
#21
Lexus Test Driver
I might think of doing that for my next MPS4S XL version tires on the rears. Just worried the sidewall might be too short? How does it look as the rear sidewall might be short by about 1 inch? Is there a close up picture of the rear tires? Did you feel any negative impacts on handling with the shorter sidewall?
Smaller tire changes the effective final drive making it higher effective gear. The factory 2.937 is now effectively a 3.05. It’s only a 3% increase but that’s what they did on the 2029 which was a 5.5% increase.
Lexus claims an improved 0-60 time of just under 4 seconds thanks to a higher final-drive ratio (3.13 versus 2.97) and a new launch control system. Off-the-line acceleration does feel peppier (even without using launch control),
Lexus claims an improved 0-60 time of just under 4 seconds thanks to a higher final-drive ratio (3.13 versus 2.97) and a new launch control system. Off-the-line acceleration does feel peppier (even without using launch control),
#23
Lexus Test Driver
#24
I like a square set up myself and wondered what the sizes on this car might look like, thanks for the info.
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#26
TVD what is better to run in 1/4 mile Slalom or Track ?
Yeah, slalom mode is my mode of choice in city driving where maneuverability is everything on narrow roads. It really increases on-center steering response. A flick of the steering by an inch generates an instantaneous response. Essentially, it gives a very short wheelbase feel in slalom mode. I find it far more enjoyable than track mode in city driving. I could understand on wide and long turns, track mode is the one to use to get the rear to rotate so that the nose can be pointed inwards, but in every day driving slalom mode is the one to use.
#27
Lexus Test Driver
You mean 1/4 mile run? TVD mode will not change your 1/4 mile one way or the other based on my own Dragy GPS runs and just based on what TVD's intended purpose is. It is about improving turning performance and making the car have a more rear-bias center of rotation. Either TRACK or NORMAL mode would be fine for 1/4 mile runs. SLALOM mode would be less recommended because if the car wags its tail, the steering is much faster in SLALOM mode so if you try to correct the fishtailing, corrections could have an adverse affect.
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#28
Slalom Mode
You mean 1/4 mile run? TVD mode will not change your 1/4 mile one way or the other based on my own Dragy GPS runs and just based on what TVD's intended purpose is. It is about improving turning performance and making the car have a more rear-bias center of rotation. Either TRACK or NORMAL mode would be fine for 1/4 mile runs. SLALOM mode would be less recommended because if the car wags its tail, the steering is much faster in SLALOM mode so if you try to correct the fishtailing, corrections could have an adverse affect.
#29
Slalom is better because it will direct the power to the wheel that is not slipping FASTER than any other mode - i.e. its the best at limiting/eliminating wheel spin.
#30
Slalom mode and eliminating wheel spin from the launch makes sense for the ET but why is the trap also higher? How does slalom mode affect MPH?