Tyre pressure Lusso & Lusso T?

I am able to calculate a pressure advice for you but need some data for it.

From car :
1. weights on axles , mostly Max permissable axle weight, given on a metalish plate , I think must be on the car since 1980 ( at least in Holland it is , but think law is for Europe).
Then MPVW ( max perm vehicle weight), and Empty weight of car, and the way you load it fo rthe situation you want to have advice pressure for.
2. Maximum speed you use and wont go over for even a minute ( so be honnest).
3. eventual alighnment , camber angle , but only if above 2 degr +-. mosty not that important

From tyres:
1. Maximum load or Loadindex
2. Kind of tire to determine the reference-pressure/presure needed for the maximum load up to 160km/99m/h. Personal car tyres are made in Standard load with mostly 2.5 bar.36 psi referencepressure. XL/reinforced/Extraload tyres reference-pressure mostly 2.9 bar/42 psi.
3. Speedcode of tire ( for your car probably V W Y or even (Y) but begins for normal car tires with Q rest R S T H.)
But also give sises then I can google, all can be found on sidewall.

The more acurate you can give the weihts , the more we can play with the reserves.

Greatings from a "Dutch Pigheaded Selfdeclared Tyrepressure-specialist"
Peter

 

Googled your sise of tyre and found XL in 105 loadindex wich stands for maximum load of 925kg/2040 lbs and official system gives for Y speedrated that you can drive 220km/h with a pressure of 2.9 bar/42 psi with that maximum load of it. most low Hight width division tires are XL.

But my pigheaded idea is that this maxload AT 42psi only you can drive 160km/99m/h, and for higher speed the AT 42 has to be highened up in the official system.
But even for that I am pigheaded, and use my own determined system , that is simpler .
For higher speed then 160km/99m/h you have to lower the Loadindex by one step for every 10km/6.5m/h .
this gives higher pressure then the official system so never unsaver and simpler to determine

Your given 130m/h I converse to 210km/h for easyer calculating for me ( in Holland we use KG and km/h).
so the loadindex of 105 must be lowered by (210-160)/10= 5 steps to 100 Li stands for maxload 800kg/1765 lbs .
2 tires on the axle means to fill in the formula 1600kg/3530 lbs.

You did not give the MPAW's front and back and your 1650 kg is probably your empty weight.
I wonder how you all know so exactly the weigtdistribution ( the F51/R49%).
Is that empty weight, or weight filled with all the load and persons.
Or mayby even the MPAW in relation to the MPVW.

the original 255 googled as LI 100 and the 275 as 101 Y and 105 V, so there suprisingly a difference between LI in V and Y . V uses 160km/h as referencespeed and Y 220km/h.
In my system Y speedrated would give 6 LI steps lower for Y then V but the 4 here I can live with , because my system is a rule of tumb.

Now I only need the right weights to use, so give if your 1650 kg is empty or whatever.

 

You must mean the MPS4S, not the MPS4. The MPS4 is a different tyre from the MPSS and MPS4S only sold here in Europe specifically made for the hot hatch market.

 

Do you mean you have to lower the load index for increasing speed? I thought it should be the other way around. I'm confused.

 

@ otaki
For the same tire you need to lower the Loadindex for higher speed.
This gives in the end higher pressure, so lesser deflection so lesser heatproduction a cycle .
This lower heatproduction a cycle X more cycles a second= is the same heatproduction a second , so same hottest temperature of the rubber .

What you are confused with , I think, is that you think for higher speed you need a tire with higher loadindex and that would not even be bad.

 

First the weights :
1650 kg is empty weight with tank fileed, but no driver in it.
this is devided 51% F and 49%R, so you calculated that out of the weighted axleloads.
And those where , as I calculated back.
Front 841.5 kg and rear 808.5 kg .
Driver in front 80kg devided 55% front and 45% rear ( gravity point of a in car sitting person about at the belly buttum I once determined)
Or it must be that the Ferrari is somewhat else build as the average car, where driver and co driver seats are about half way front and rear axles.
Gives 44 kg front and 36 kg Rear.
Together Front 885.5kg and rear 844.5 kg .
To this we add 10% for maximum reserve with still acceptable comfort and grip and also you need this for unequall weightdivision R/L, and pressure loss in time, and misreadings ,and etc etc.
Gives weight to calculate with in the formula Front 974.5 kg and rear 929 kg.

then the tires. the remark in my former post about the same sise in 101Y and 105V , must be a mistake and that the 101 Y was not an XL tire but standard load.
Found same for your 285/35/20 , one did not give XL and gave 100 Y LI and other 104Y and XL but yet another gave ( TOYO) gave 100Y in XL.

So I think the data given by that tYre-seller was not always correct, because I never seen different LI in same sise of tire in XL .
But because you read the specifications from sidewall we will go from that.
Front 104 Y wich is for my calculations you can drive with 900 kg on the tyre 160km/99m/h with pressure 42 psi/2.9bar without overheating the tyre at any spot .
REar 105Y means you can drive with 925 kg on tire that 160km/99m/h AT 42 psi cold pressure without overheating the tires.

for your 130m/210km/h you say you drive (but when) , we substact the 5 LI so next.
Front LI 99/775kg Rear LI 100/800kg

We calculate per axle so double the tyres maximum loa , and I will calculate with the European official formula, because for SL and XL// tyres this is pretty good formula to laws of nature.

If your max speed is not for even a minute 160km/99m/h
Front (974.5 /(2 x 900))^1.25 * 42 psi=19.5 psi rounded up 20 psi.
Rear ( 929kg/(2 x 925))^1,25 X42 psi= 17,75 psi rounded up 18 psi

If your you wont go over 210km/130m/h for even a minute next
Front ( 974,5/(2X 775))^1,25 * 42psi = 23.51 psi rounded up 24 psi.
Rear ( 929 kg/( 2X 800)^1,25 * 42 psi= 21.28 rounded up 22 psi.

Mind that this is only for when you are alone in the car.
My advice would be , also if your max speed is 160km/99m/h the highest so F24R22psi.
But because you have pretty oversised tires you can do with this low pressure.

this pressure might give already some bumping, but this is subjective.
Because the advices of car makers is high nowadays , people think the discomfort of cars is what is normal .
Fuel efficiëntie is better at higher pressure, so wiht these pressures you migh spoil some more fuel.
And if you once take some more people or heavy load , and you are not able to fill higher pressure, then keep yourselfes to lower speed , for instance max 120km/75m/h , so this pressure is still enaugh to not give overheating of tyres.

Sorry for the long story , but this way the others can see what they need to give , and see how it is determined.