[arpad_m]

Thanks again, good Sir. You know what would be super cool, though? An Excel sheet where one can plug in parameters like corner weights, tire ratings, maybe even max tire pressures, and it would generate a proper graph of speeds/loads as a function of tire pressure, somewhat similar to your initial one but with cold tire pressures on the X axis and max speeds/loads on the Y axis.

I know it's a bit of work, and I can't offer much in return, but I put together a makeshift E85 calculator in Excel, it shows resulting percentages depending on vehicle parameters and how much E85 and gasoline one puts in the tank, plus it even highlights the "safe zone" in green given a max E percentage, see below. Not sure how useful it would be to you, but that's all I have

[jadatis]

Something like this?

https://1drv.ms/i/s!AtzmkuDu4Calij67lxRPkWsWhJVt



Made it for RV, with slightly different max speeds and pressures then a Camaro.
Can be found in next map on my onedrive, that belongs to myhotmail. com adress with username jadatis ( like this to prevent spamm, combine yourselves).
The spreadsheet can be found in next map
https://1drv.ms/f/s!AtzmkuDu4Calhy1JOdG0mFbnyEF9
If spreadsheet is protected, it has no password, so you can unlock it and adapt it.
But dont do it in the claud, first download it to your computer, and open it in Excell or similar program on your computer.

[jadatis]

Now realise we are hyjacking this topic, but topicstarter fun has his answer.

Was a bit of work copying and pasting on right place to give 3 tires in one list.
Used 250kmph/155mph max speed, you wont go over for even a minute.
Comfort on roads you drive this speed stays upto higher pressure still acceptable to my idea.

Check if curent set rear is realy SL, see if you find on sidewall XL/reinforced/extraload.
For me its strange that 305/35 gives same loadindex in SL then 315/30 in XL.
If both XL more logical then 1 step smaller section width is compensated by 1 step higher asect ratio.
But if so, this is then what tiremakers decided, so we have to use it. We then have to assume they did it to natures law right.

Gave above original loadindex and loadrange (XL or SL) but used the 10 steps reduced for the calculations. So only needed to give 3 sets. Gives 95% of calculated axleloadcaacity, so a little less reserve for things like unequal load R/L, inacurate reading of pressure and weight, pressureloss in time, etc.

So for curent set ( CS) use FR 104XLand Rr 104SL behind cold psi given.
And for planned set (PS) FR 102XL in front of cold psi, and 104XL direct behind cold psi.

102XL PS/ cold PSI/ 104XL/ 104 SL CS
Axleload/cold PSI/ axleload/axleload
1062 lbs/ 15 psi / 1130 lbs / 1300 lbs
1122 lbs/ 16 psi / 1194 lbs / 1374 lbs
1182 lbs/ 17 psi / 1257 lbs / 1447 lbs
1242 lbs/ 18 psi / 1321 lbs / 1520 lbs
1302 lbs/ 19 psi / 1384 lbs / 1593 lbs
1361 lbs/ 20 psi / 1447 lbs / 1665 lbs
1420 lbs/ 21 psi / 1510 lbs / 1737 lbs
1479 lbs/ 22 psi / 1573 lbs / 1810 lbs
1538 lbs/ 23 psi / 1636 lbs / 1882 lbs
1597 lbs/ 24 psi / 1698 lbs / 1954 lbs
1656 lbs/ 25 psi / 1761 lbs / 2025 lbs
1714 lbs/ 26 psi / 1823 lbs / 2097 lbs
1773 lbs/ 27 psi / 1885 lbs / 2168 lbs
1831 lbs/ 28 psi / 1947 lbs / 2240 lbs
1889 lbs/ 29 psi / 2009 lbs / 2311 lbs
1947 lbs/ 30 psi / 2071 lbs / 2382 lbs
2006 lbs/ 31 psi / 2133 lbs / 2453 lbs
2064 lbs/ 32 psi / 2194 lbs / 2524 lbs
2121 lbs/ 33 psi / 2256 lbs / 2594 lbs
2179 lbs/ 34 psi / 2317 lbs / 2665 lbs
2237 lbs/ 35 psi / 2379 lbs / 2735 lbs
2294 lbs/ 36 psi / 2440 lbs / 2806 lbs/SL referencepress
2352 lbs/ 37 psi / 2501 lbs / 2876 lbs
2409 lbs/ 38 psi / 2562 lbs / 2946 lbs
2467 lbs/ 39 psi / 2623 lbs / 3016 lbs
2524 lbs/ 40 psi / 2684 lbs / 3086 lbs
2581 lbs/ 41 psi / 2745 lbs / 3156 lbs
2639 lbs/ 42 psi / 2806 lbs / 3226 lbs/XLreferencepress
2696 lbs/ 43 psi / 2867 lbs / 3296 lbs
2753 lbs/ 44 psi / 2927 lbs / 3366 lbs
2810 lbs/ 45 psi / 2988 lbs / 3435 lbs
2867 lbs/ 46 psi / 3048 lbs / 3505 lbs
2923 lbs/ 47 psi / 3109 lbs / 3574 lbs
2980 lbs/ 48 psi / 3169 lbs / 3644 lbs
3037 lbs/ 49 psi / 3229 lbs / 3713 lbs
3094 lbs/ 50 psi / 3290 lbs / 3782 lbs
3150 lbs/ 51 psi / 3350 lbs / 3851 lbs

[arpad_m]

Originally Posted by jadatis

Now realise we are hyjacking this topic, but topicstarter fun has his answer.

Was a bit of work copying and pasting on right place to give 3 tires in one list.
Used 250kmph/155mph max speed, you wont go over for even a minute.
Comfort on roads you drive this speed stays upto higher pressure still acceptable to my idea.

Thanks again very much, jadatis. According to this table, I wouldn't really need to raise cold pressures for a top speed run very much, even using the standard street recommendation of 32 psi yields ~4250 pounds---but this is for 155 mph, isn't it? I know I'll only be at top speed for a few seconds, so maybe the table is still safe to use, but how did you reckon to use 155 mph?

Originally Posted by jadatis

Now realise we are hyjacking this topic, but topicstarter fun has his answer.

Was a bit of work copying and pasting on right place to give 3 tires in one list.
Used 250kmph/155mph max speed, you wont go over for even a minute.
Comfort on roads you drive this speed stays upto higher pressure still acceptable to my idea.

Check if curent set rear is realy SL, see if you find on sidewall XL/reinforced/extraload.
For me its strange that 305/35 gives same loadindex in SL then 315/30 in XL.
If both XL more logical then 1 step smaller section width is compensated by 1 step higher asect ratio.
But if so, this is then what tiremakers decided, so we have to use it. We then have to assume they did it to natures law right.

Don't worry about hijacking, as you said, the OP's question has been catered to.

I know, right? SL doesn't really make sense, but I did double-check the tires a minute ago, and only the fronts (285/35/20) have the extra load designation on the sidewall. The rears (305/35/20) have an older "velvety" sidewall design, too, with the race flag pattern "etched" into the rubber, while the fronts are straightforward and have a flat sheen all around. To me this indicates they belong to a different subfamily within the PS4S, so it's plausible that their load class would also differ.

[jadatis]

You mentioned that 200mph try, so I went for 250kmph/155mph.
Assumed you normally drive mayby 90mph constant, 10 mph higher then allowed in US, as far as I read. Then tire-material not 120degrC/250 degr F, but verry roughly estimated 75 degr C / 167degr. F. Then that 20 seconds going to 200mph, wont highen up the tire material to above 250 degrF, wich is the critical temperature above wich rubber hardens, and beginning cracks are made, that tear further in time, untill mayby only after 2 years that far, that tire blows or treath separates.

So this is only allowed " Zero" times in tires use.

The 155mph is what Porche often limits speed in motormanagement, so they can recomend a lower pressure, amongst other things.

Theoretically if you drive 155mph constantly with these pressures from list, tire material not above 250 degr F, at any spot of tire.

If pressure filled at 20 degr C/ 68 degr F and driving in 40 degr C/ 104degr F ambiënt temperature the temperature of gascompound goes to about (my estimation) 75degr C/167 degrF, with the pressure rising belonging to that wich gives lesser deflection, so lesser heatproduction.

This is an other part of the story.
At ambiënt temperature of 68 degr F, temp in tire about 60 degr C/ 140 degr F and tire material still not above 250 degr F.

So never blead down cold or warm pressure on a hot 104 degr F day.
The tire needs the lesser deflection the higher pressure gives to produce lesser heat, so heating up and cooling down stays in line, so tire material wont overheat.
Cooling down of tire material is dependent on temperature differences between tire-material and in and outside tire air./gascompound. First I thought speed also because of airstream, but at the ground, tire is standing still. Top of tire more then 2 times as fast as you drive, but covered.

There are 2 camps in this.
Largest camp says to fill determined needed cold pressure at ambiënt temperature, whatever it is, 32 degr or 110 degr F.

I am in the camp to calculate back to an index temperature, before comparing it to determined needed.
Made spreadsheet on mobile to calculate pressure change for temperature change, and the other way around. And for if completely dry gascompound in tire( like Nitrogen lobby claims), and if enaugh water in tire, like normal air without a compressorvelssel in between, in wich I am first, I think.
I cripted my mail adress already in former post, so if you like to play with it, mail me, and I will send it in return.

But here a list assuming 70 degr F index temperature and gives degr F/1psi chanche.
Easy to calculate by head and acurate enaugh, and you only have to remember fir your filled pressure.

20 psi/ 15,5F/psi
21 psi/ 15F/psi
22 psi/ 14,5F/psi
23 psi/ 14 F/psi
24 psi/ 13,5F/psi
25 psi/ 13,5F/psi
26 psi/ 13 F/psi
27 psi/ 12,5 F/psi
28 psi/ 12,5 F/psi
29 psi/ 12 F/psi
30 psi/ 12 F/psi
3 1psi/ 11,5 F/psi
32 psi/ 11,5 F/psi
33 psi/ 11 F/psi
34 psi/ 11 F/psi
35 psi/ 10,5 F/psi
36 psi/ 10,5 F/psi
37 psi/ 10 F/psi
39 psi/ 10 F/ps
40 psi/ 9,5 F/psi
42 psi/ 9,5 F/psi
43 psi/ 9 F/psi
45 psi/ 9 F/psi
46 psi/ 8,5 F/psi
49 psi/ 8,5 F/psi
50 psi/ 8 F/psi
53 psi/ 8 F/psi
54 psi/ 7,5 F/psi
58 psi/ 7,5 F/psi
59 psi/ 7 F/psi
63 psi/ 7 F/psi