Correct tire pressure downsizing wheels

[sleepermk7]

Went from stock size 225/40/18 to 235/45/17.

Load index of my 18s is 92 and the 17s are 94.

Stock tire psi cold is 37psi.

Should I fill the 17s to around 35 psi or lower?

 

[manu97]

https://tiresize.com/pressure-calculator/

 

[sleepermk7]

https://tiresize.com/pressure-calculator/

30 psi seems way too low.

 

[manu97]

30 psi seems way too low.

I’m running 34 on cold 245/40R17. Maybe the extra sidewall lowers the pressure?

 

[krs]

30 psi seems way too low.

(225/40R18 XL) Load Capacity: 1254 lbs. @ 37 psi.
(235/45R17 SL) Load Capacity: 1270 lbs. @ 30 psi.

There's more to the number than just what you see. Read through the rest of the information. That 30psi matches the load capacity of your OEM tire, there's more to psi numbers. The higher the psi, the higher the capacity within the index rating and range.

30 psi is a basic starting point.

 

[GolfRRRR1]

I use this guide a lot.