R888R tire pressures

[Ujjwal]

I'm looking for suggestions on optimal pressures to run for a 235 40 17 r888r. How high is too high, and what's the sweet spot? For measuring methodology, is absolute pressure a more important metric or is relative pressure rise more important after a session with the goal of trying to set a hot lap (I.e. to account for a cold or hot day).

[jimmo-san]

Ujjwal, just as a completely unscientific reporting result, here are my last readings, at 32 psi, on the R888 as measured by an Intercomp tire pyrometer from one of the events last year (can't remember which one, it's in the Intercomp memory). All temps are outside-centre-inside, in degrees F. I generally pay attention only to the difference between the three readings, since getting a tire temp right off the track is not that easy. Others may disagree.

LF: 143/142/135 RF: 132/136/134
LR: 134/143/127 RR: 127/130/128

LF: 133/135/132 RF: 128/123/126
LR: 126/129/131 RR: 119/121/126

LF: 131/134/128 RF: 124/126/128
LR: 123/127/130 RR: 118/125/126

205/45R16 Toyo R888s on an 8" rim. Mazda Miata with rear camber set within FSM specs. I've generally found 32 psi feels good for me. Again, others may differ.

[Ujjwal]

Thanks for the data! I'm glad I asked on this forum as it would have taken me probably 2 more events to have enough track time to gather data to go from 40s to low 30s hot.

[egroenke]

From Toyo's Website:

SETUP & CARE


Toyo Tires recommends the following general setup guidelines for the Proxes R888R:

• Operating Temperature: 160°F to 220°F
• Hot Inflation Pressures: 32 to 38 (psi)
• Camber: -1° to -3°
• Caster: As much positive as possible

For recommendations on proper use, handling and storage of this tire in colder climates, please click here.

On My 2008 STI with -2.3 Front Camber (daily driven) and -2 rear camber (0 toe) I've found ~34-35PSI hot is the sweet spot. It's matches up well to the R888's (not R) that I ran a few times on our LGT SpecB race car as well.

I have tire temps scribbled away as well (not close by) from the GP track as well.

[Ujjwal]

I found 36psi hot to work best for a ~3100 lb car, 235 40 17 on a 7.5 inch rim. Higher or lower by 2 psi majorly affected the lap times. I may not have found the perfect pressures yet because datalog shows these have less lateral grip than a 255 40 17 rs3.

[mustturn..right]

Hi, just a reference point; regardless of the tire, I start at 10psi per 1000lbs of vehicle weight (Cold) and go up or down from there. With Toyo RR, I ended up with 34 cold, 36 hot. With the R888R, it was 2psi more. But that also changed from cold track to hot track. (3200lb vehicle)….the type of driving event also matters.
also note the OEM recommendation for temps are while on track, not necessarily after a cool down lap and back to the pits.

hope this helps…may be a old thread but this good to have around

[jimmo-san]

hope this helps…may be a old thread but this good to have around

Old threads never die ... they just get better with age. :-)