jaseman

Wass wondering if anyone had PSI recomendations for the snow tires on my IS-300?

Just put 16" Blizzack WS-70's on it. The came mounted and balanced from TireRack @ 30psi which seems a bit low. I took them up to 40psi for the moment, but was wondering what everyone else was running their snows at...

mitsuguy

iTrader: (2)

What is the size, and, more importantly, the service description? IS300's call for 33 psi with the OEM 17's, unsure of the pressure on the OEM 16's (yes, a couple came with 16's)...

At any rate, the service description is the number/letter combination after the size (something like 93S or 95T, is what I am looking for...

With that service description information, we can then give you the minimum pressure, and of course the maximum is listed on the sidewall of the tire...

as a general rule, 35 psi is where almost all passenger car tires carry their maximum weight, so, your 40 psi is more than necessary, for sure. The area above 35 psi up until the max air pressure on the tire is so you can tune vehicle handling and tire wear... Chances are with 40 psi on a relatively light IS300, you will wear the center of the tires prematurely...

jaseman

The snows are 205/55/16 91T

(originals are 215/45/17)

Just trying to eliminate some of the vague feeling the snows have (though I don't expect them to feel the same as summers or all seasons).

mitsuguy

iTrader: (2)

So, with that, you can run anywhere from the factory recommended 33 psi all the way up to the max inflation pressure on the sidewall of the tire... Personally, 35ish should be fine... 40ish will be higher than necessary and may wear out the center of the tire faster, but, would result in a little sharper turn in...

Completely up to you, if it was my car, 35 would be what I ran...

jaseman

Thanks.
I'm gonna try that as a good starting point, and adjust for 'feel' from there.

vwynn

iTrader: (4)

you would have to cross you OE spec load index/psi to the new one which is 91. (XL and nonXL matters) to get the "exact recommended psi" .

your door is the best place to check for OE PSI recommendation for the OE tires. then you find if that PSI is for XL or non XL... then you convert PSI to how many lbs it can hold for that size tire.. then you find your new size and cross the lbs it can hold to PSI to match it n voila.. your recommended PSI for your snow tires.

Cheers

ps. ive just given you a quick run down but yea..

mitsuguy

iTrader: (2)

If ya wanna get that technical, we would also need to know of the standard tire was a euro metric or p-metric tire... the reality is, that the OE load index was 87 for the 17" OE fitment and 89 for the OE 16" being that we are at 91 here, anything at the stock air pressure recommendation (33) and above, we are good, as I noted already...

vwynn

iTrader: (4)

forgot about the euro/pmetric.

Good catch!

zig@tr

The 30 PSI is just a standard inflation for the mounting machines, there should have been an installation packet included with your wheels and tires which indicated you need to change to the proper PSI. Typically for a winter wheel/tire package it is always recommended to run the OEM inflation on your driver side door placard. I would definitely back off from 40 PSI as you are going to prematurely wear the center of your tires.

Air Pressure - Correct, Underinflated and Overinflated