Sumitomo HTRr ZIII 225/40/18. And 285/35/18 what should I run for tire pressure? they are sitting at 22 frt 25 rear. max rating is 51.

 

Whatever is your personal preference, between 2 and 3 bar. I like 2.5 bar, good grip and not too harsh. 'Normal' family cars run around 2.2, 2.3.

 

For Street/Highway on street tires 36F and 34R cold. The highest to not get center tread wear.

For Autocross 28F&R they heat up to 34psi. Settled on 28 because 34 hot was the most I could run without the center of the tread blistering and 28 is what they cool down to.

 

thanks! sounds good to me!

 

+1

 

If you work on the principle that each corner carries 400kg, you can use the max load at max pressure proportionately to give you an idea of the range of possibilities.

You rear tire pressure looks reasonable given the size -the front ought to be proportionately higher I would suggest- probably about 35 psig but of course it also depends on type of useage.

Regards

Fred

 

+1. I keep mine at 36F/34R for everyday use. Track use 28/29, warm them up gently the first lap or 2. Then they will be 36/34. But I am running 17" wheels. Possibly 18's will expand less, as there is less air in them.

You can see in my photo below some white shoe polish applied to the shoulder of the tires to monitor tread roll over. 36/34 is what always worked best for me.