Understanding tyres and tyre pressures

[SouthernLead]

Hi,

I want to get a better understanding of the spec of my wheels/tyres and how that relates to tyre pressures. I've attached a photo of my placard, but have some specific questions.

I have 225/40 R18 wheels (Sport suspension), I can see those listed on the placard, but what do the letters after that refer to? E.g. "92Y XL" or "92V XL M+S"?

I assume the rows in each section refer to the load/weight of the vehicle? E.g 3 persons/1 bag, or 5 person/3 bags. Etc. But what does the book icon with the "i" on it indicate?

At the bottom, there are two lines reading "T 125/70 R16" and "T 125/70 R18" with another recommended pressure setting? What is this referring to?

Given that normally there are 2/3 of us in the car, with little/medium luggage, I assume I should be aiming for the top row of the placard? E.g. Front 36psi, back 33psi.

Any help with these questions really appreciated.

Thanks,
Andy.

 

[KrisKrk]

91 and 92,93 ... is the load index per tyre. Letter after that number is the speed index for the tyre.

Have a look here:

https://www.hometyre.co.uk/tyre-information/tyre-styles

Also, check your handbook for the explanation in regards to those extra loads with the book and "i" mark or M+S.

I never looked at these stickers as my wheels were not listed, on the cars I owned. Will check current car, tho.

You need to make sure you have correct tyre pressure according to the season also

 

[desertstorm]

"T 125/70 R16" and "T 125/70 R18" are the dimensions of the tyre on a spacesaver spare. So if you have one of these they need to have 61 PSI in them.
I should read the manual regarding tyre pressures as to what the "i" means . Possibly slightly lower tyre pressures for a smoother ride at the expense of mpg.
M+S is mud and snow so essentially a tyre designed for winter conditions.