amblyn

Wondering what everyone fills there tires up to. I have the factory recommended size tires on and inflate to 37psi

gigapipe2

On the side of the door. It says 30psi.

amblyn

mine kinda look flat when down near 30 psi i dunno haha in my head i get better mpg with higher inflated tires. is that bad?

wing0

Usually overinflation cause middle portion of tread to wear faster.

hypervish

30 is for the OE Tires that come with the car.

hypervish

I'm running about 35 psi cold. If I'm in a blizzard, or a bad snow storm I will knock the psi down to about 32 hot.

gigapipe2

Would it be cool 35 in the back and 32 in the front?

lexrally

Above the recommended PSI (30) might save gas, but is it possible that over inflating tires for extended amounts of time can cause front-end suspension issue (not to mention uneven tire wear)? Also, my tires are at 30 psi, and have nitrogen in them. The tire shop said that as long as they are kept at that psi and rotated, the warranty will be valid.

roostonu

It depends on the tire and it's load capacity. Not all 225/70/16 tires have the same capacity. It also depends on the weight of the vehicle. The same tire on a 3k lbs. car will take less pressure than on a car that weighs 4k lbs. There isn't a magic number for each vehicle and tire combo. The proper inflation is one that creates the maximum contact with even wear. If you are overinflated you will wear the center portion of the tread more and under inflated will wear the outer edges more. As long as you don't exceed the weight capacity or maximum PSI that is stated on the side of the tire, you shouldn't have warranty issues. If you run 30 psi in a tire that has a higher capacity and a max pressure of 60psi, you will be under inflated and not getting the best mileage out of your tires or fuel.

The best way to determine the proper pressure with new tires is this;
New tires have little rubber protrusions across the entire tread that wear off very quickly. These are the gates that allow air out during the molding so that the mold fills up completely without any voids. They are also very early indicators of how well your inflation is set as well as how well the vehicle is aligned. Provided the alignment is correct you can use these little nipples to fine tune your PSI. The only tires that I've seen wear evenly with 30 psi is over sized off road tires so I usually start car tires around 34-36 depending on the size of the vehicle. (The lowest max pressure I have seen on modern tires is 44 psi). Then you watch very closely how the nipples wear off the tread. It happens quickly so I would check them every 5-10 miles. If you see the center nipples wearing sooner, let 3 psi out at a time and if you see the edges wearing sooner add 3 psi until they wear off evenly.

There you have it in a nut shell. One thing worth noting is; If you are loaded to the max capacity of the vehicle you should probably be somewhere near the max psi stated on the tire. Also if you are real precise with the above method of determining the proper psi, you should probably end up with a couple more pounds of air in the tires that support the weight of the engine. Unless of course you have a truck that is loaded in the back.

Lexmex

39 but I have 235/70/16 Michelin Crossterrains that allow for a max of 44

amblyn

My max is 44 also at 30 psi sides of tires kind of buldge out looking low soo fil to 37 an odd number but figure less friction better gas and tire looks like meets ground evenly at 30 looks like edges touch to much and at 37 more flat tire to roAd connection better turn response also even though the turning radius on rx300s is horrible make alot of unnecassary 3point turns due to that

mckellyb

I just had 5 BFG A/T ko's, OEM size, put on my wife's '02, and the shop put 44 PSI in them. They're rated for 50 PSI, but I wanted 38-40, anyway, so I'm not complaining.

They'll wear just fine, honestly, even at this pressure.

mckellyb

Actually, with front-wheel-drive vehicles...and even if yours is AWD, it's essentially FWD, you want slightly higher pressure in the front tires.

More weight up there, with both engine and transmission in front of the occupant's feet, than in a 'traditional', RWD vehicle.

SethP

This.

Assuming you're using an OE fitment.....

It doesn't matter what the side of the tire states as "max PSI" - these tires are made for a wide variety of cars, and each car may have a different recommendation for the same tire. This is a MAX, nothing more.

The recommended within the door panel accounts for the weight of the car, to then give you the optimal PSI to ensure proper and even tread wear and grip. Over inflation WILL cause the middle to wear faster, and it puts less tire surface on the road. This takes away from the amount of grip you have on the road.

Sure, you may get 1/3 of an mpg extra, but in exchange you get less grip on the road, and uneven wear on your tires. In no way is it worth it, nor is it recommended by any of the OEs (their recommendation is in the door)

It still blows my mind that ppl even read what the tire says as MAX PSI when deciding how much air to put in.

SethP

This is a bad idea....

You want more traction in the back vs the front.

By over inflating the back, you reduce the traction in the back. The back being the stability of your vehicle.

This is extremely closely related to the discussion around where to put 2 new tires. You will find that all of the tire manufactures recommend putting 2 new tires in the back, and they've actually proven that putting two new ones in the front is very dangerous in the rain, and can lead to crashes. Ignore what all the self proclaimed experts say on this, the tire manufacturers are all in agreement on this one, and have tons of facts on their side from countless tests.

Increasing the PSI in the back vs the front is in essence simulating this effect.

There are vehicles which specify different PSIs in the front vs the backs, the RXs are not one of those. I don't know why everyone is always convinced they know better than the OEs, or in this case, Lexus.