Recommended Tire Pressure?

[Blue By You]

I like to pump up my tires a little bit to protect my wheels from poor roads and such. But want to avoid going too high.

What are you all running for cold tire pressures on the street for spirited driving?

[640ijims]

If MPSS's -21" and you are concerned about even wear across tread…assuming you've had a four wheel alignment, 39# front & 40-41# rear cold , with accurate gage. On my second set, ran first ones at 36# & had outer edge heavier wear at all four corners

[Blue By You]

Originally Posted by 640ijims

If MPSS's -21" and you are concerned about even wear across tread…assuming you've had a four wheel alignment, 39# front & 40-41# rear cold , with accurate gage. On my second set, ran first ones at 36# & had outer edge heavier wear at all four corners

That's where I was at and pumped them up to 40F/42R but I'll back them off a bit. Thanks

[640ijims]

Check tread wear every 1000 miles with accurate tread depth gage …up or down pressure based on reading across all four or five ( on third Chardonnay so hard to remember) grooves

[Gossypiboma]

The sticker on my 18' door jam says 36psi front and rear.

[640ijims]

Your car your decision

[Longboarder]

The lower you go the larger the contact patch and more grip. Higher you go the smaller contact patch less grip but better mileage. Extreme ends too low or high will cause uneven wear.

There is an optimal point for everyone. I like to stay on the low end in the mid 30's. This is a performance suv so i like to get max cornering grip. I'd prefer less grip using launch control as it bogs pretty badly even when tuned so I think higher pressure might be better to get it to spin just a tad but I haven't done any testing yet.

Tire pressure is a really big deal. On my performance cars I stay really low as I only care about grip. Low 20's in my modded 991 Turbo S and idc that the tpms light stays on. 0-60mph in 2 flat on the street. At the factory tire pressure there is zero grip using launch control just spins wildly. That's quite a difference with just tire pressure.

[Blue By You]

Originally Posted by Longboarder

The lower you go the larger the contact patch and more grip. Higher you go the smaller contact patch less grip but better mileage. Extreme ends too low or high will cause uneven wear.

There is an optimal point for everyone. I like to stay on the low end in the mid 30's. This is a performance suv so i like to get max cornering grip. I'd prefer less grip using launch control as it bogs pretty badly even when tuned so I think higher pressure might be better to get it to spin just a tad but I haven't done any testing yet.

Tire pressure is a really big deal. On my performance cars I stay really low as I only care about grip. Low 20's in my modded 991 Turbo S and idc that the tpms light stays on. 0-60mph in 2 flat on the street. At the factory tire pressure there is zero grip using launch control just spins wildly. That's quite a difference with just tire pressure.

Although I'm looking to protect my wheels from these crappy roads, I also want as much grip as possible like you. Something to consider, thanks.

[Longboarder]

Originally Posted by Blue By You

Although I'm looking to protect my wheels from these crappy roads, I also want as much grip as possible like you. Something to consider, thanks.

You just jogged my memory on another item.

The lower the tire pressure the more comfortable the ride too. My X5M is in south orange county California where the roads are the best I've ever seen. So I can get away with really low pressure since the roads are great and very little risk of bending wheels.

I have a home in another country in a hot/rainy environment and the roads are insane HUGE potholes all over and I have to run higher pressure on my SUV there just so the wheels wont bend. Performance has another meeting down there.

[Yuille36]

But running too low of a pressure will lead to excessive tire wear on the outer edges.

[Longboarder]

Originally Posted by Yuille36

But running too low of a pressure will lead to excessive tire wear on the outer edges.

Agreed but for those wanting max performance it's a worthy trade-off.

[640ijims]

Longboarder…call TireRack and run your "underinflation gives better contact patch" theory by them. Last I knew it was true in sand and snow.

[Yuille36]

Originally Posted by 640ijims

Longboarder…call TireRack and run your "underinflation gives better contact patch" theory by them. Last I knew it was true in sand and snow.

This is what we did in the military for mud, sand and snow. I do understand your theory, as they been using this method in drag racing, but there vehicles don't weigh 5000+ lbs.

[640ijims]

Drag guys run treadless tires…slicks & they ARE aired to give a flat contact patch… under inflation gives a convex tread patch. You want all the rubber, treadless or not in contact with road or track.. hence the term " contact patch"

You are correct for mud/ snow/ sand though if you judiously apply power

[M5_508]

I go 36 on fronts and 38 in the rear -MPS

[Longboarder]

Originally Posted by 640ijims

Longboarder…call TireRack and run your "underinflation gives better contact patch" theory by them. Last I knew it was true in sand and snow.

Under-inflating my Cup2's dramatically helps lap times in my GT3. Start pressure 25 front and 24 rear come in and bleed down after a few laps to maintain high 20's. Also on my 991 Turbo S low 20's in the rear gets the car to hook up on launch control 0-60mph in low 2's every time. At the manufacturer setting the tires spin wildly. So yeah, lower pressure = larger contact patch = better performance.

[Klienfeld303]

Originally Posted by Longboarder

The lower you go the larger the contact patch and more grip. Higher you go the smaller contact patch less grip but better mileage. Extreme ends too low or high will cause uneven wear.

There is an optimal point for everyone. I like to stay on the low end in the mid 30's. This is a performance suv so i like to get max cornering grip. I'd prefer less grip using launch control as it bogs pretty badly even when tuned so I think higher pressure might be better to get it to spin just a tad but I haven't done any testing yet.

Tire pressure is a really big deal. On my performance cars I stay really low as I only care about grip. Low 20's in my modded 991 Turbo S and idc that the tpms light stays on. 0-60mph in 2 flat on the street. At the factory tire pressure there is zero grip using launch control just spins wildly. That's quite a difference with just tire pressure.

Damn I didn't even THINK of this. See how good this forum stuff can be??! Sheesh. Thank you.

[640ijims]

Not wanting to be an IMHO provider, attached are a series of tech pieces from TireRack on inflation..all of us need to be aware of, sorry there are / may be out of order, no page numbers, but we're all pretty smart and able to figure out where one page ends and which is the next page

[640ijims]

Should be "Required" reading!

[8202632]

Good stuff here!

[ekological]

Just as another data point, I'm with 640ijims and run 40/39 f/r. I hadn't checked for a while and the weather has cooled, so the starting cold pressures were somewhere around 36. Worked on a lot of cars the other week and added air to get back to my usual and the difference when cruising on the highway was very noticeable. At 40 - 41, cruising at 80 - 85 mph feels effortless, whereas just a few psi less and it feels like the car wants too slow down.

[640ijims]

I excerpted TireRack articles for the post. While a long grueling read on about 7 articles, they are the treatis on inflation. Those that advocate under-inflation or over inflation , except for severe environmental activities, should read them for safety.