45 PSI tire pressure and 70 MPH = 24.3 MPG

[dcdude]

I just got my brand new 2013 and drove it from L.A. to San Diego this weekend. Before I left, I located the "correct" tire pressure on the driver's door jamb (32 PSI) and checked my tire pressure (just like our dads taught us!) I was surprised to see that each tire read about 45 PSI. I can only assume that was the "factory fill," so I didn't adjust anything.

Got in and drove the family of four plus weekend gear about 100 miles. Cruise control was set at 70 MPH. Our indicated MPG was 24.3 Needless to say, I'm very pleased with the new "gas guzzling SUV."

Any downside to running 45 PSI on-road? These are the stock 17" Dunlops or Bridgestones. My old Bronco specified 40 in the rears.

 

[JayceeP]

Possibly less contact with the pavement due to over inflation which may also be a safety issue. Would also cause uneven wear due to incorrect tire pressure.

 

[Stifler]

your kidney and center tread life span

 

[dcdude]

I'm pretty sure that Ford's "fix" to the original Explorer rollover problem was to under-inflate the tires.

 

[1engineer]

Wait til you hit some grooved pavement lol.

 

[eddiebx]

45 psi sounds a wee bit high, but I guess the only way to know if it will cause uneven tire wear is to find out. Take this with a grain of salt because I am surely not a tire expert, but I've found that for most vehicles, if I inflate it to the manufacturer spec, the tires tend to wear a bit unevenly (shoulders wear out before center) so I usually put a couple of pounds higher.

What I do is test it for a couple thousand miles until I find the sweet spot that makes them wear evenly. But generally speaking I've never needed to go more than ~5 PSI over, so naturally I'd think you're way overdoing it, lol.

If I was in your shoes, I'd probably drop it to say...38 PSI and test that out for a couple thousand miles while monitoring the tread wear and see how it looks, then go up or down from there.

 

[dcdude]

How do we explain the door jam vs. manufacturing disparity of 13 PSI?

 

[hearno]

How do we explain the door jam vs. manufacturing disparity of 13 PSI?

Manufacturing disparity? The tires were probably filled by the dealership's new car delivery tech as it was pre-delivery inspected.

 

[1engineer]

Manufacturing disparity? The tires were probably filled by the dealership's new car delivery tech as it was pre-delivery inspected.

They are shipped with 45 psi in the tires and the dealer is supposed to air them down.

OP, do this:
Go out to a parking lot with a stick of children's sidewalk chalk. Take that chalk and do a section of pavement about a foot long and as wide as your tire. Drive through the chalk and stop when the chalk section of tire reaches the top.

What are the results? Is the whole tread width covered in chalk? No? Air them down to 35-38 psi and you will be fine.

Yes, it's true a higher inflated tire will yield a higher mpg all other things being equal. Guess what: If you mount a skinny motorcycle tire to your 4Runner it will yield even higher mpg but that makes no sense, as running 45 psi running P rated tires on an unloaded 4Runner makes no sense. The premature wear will cost more than the improved mpg will save.

 

[Stifler]

chalk test > all

 

[JustinFro]

Great reco. I always did the chalk on the actual tire to see what wore off, but I like your method better.

They are shipped with 45 psi in the tires and the dealer is supposed to air them down.

OP, do this:
Go out to a parking lot with a stick of children's sidewalk chalk. Take that chalk and do a section of pavement about a foot long and as wide as your tire. Drive through the chalk and stop when the chalk section of tire reaches the top.

What are the results? Is the whole tread width covered in chalk? No? Air them down to 35-38 psi and you will be fine.

Yes, it's true a higher inflated tire will yield a higher mpg all other things being equal. Guess what: If you mount a skinny motorcycle tire to your 4Runner it will yield even higher mpg but that makes no sense, as running 45 psi running P rated tires on an unloaded 4Runner makes no sense. The premature wear will cost more than the improved mpg will save.

 

[flyrv9]

You could also wet a section of the tire with a roller and see what type of imprint it leaves on flat pavement.

Might also be interesting to see how much weight is being supported by each tire. Lets say with normal everyday loading and a full tank. You could then figure the CG and (if you really wanted to)! CG would change as gas was used, however, adjusting loading to get even tire wear would probably be more trouble than it's worth. The price of scales or load cells would probably use any savings that result.

 

[BlackWorksInc]

The tech who did the PDI (Pre-Delivery Inspection) Did NOT air down the tires properly.

45Psi is about the maximum for most P-Rated tires, you'll see a reduced traction pattern, tread life, and such... this goes back to "those people" (the Prius twits) who like to inflate their tires to bursting to get that extra MPG, while spending $$$ for a new set of tires in 30k and swearing they're not losing money...

Anyways, main point is, tire is over inflated; possible wear and safety issues are present. One more thing, Toyota's Optimism Meter is innaccurate to a degree and your actual mileage is lower than what the screen tells you.

 

[Qjake]

Toyota's Optimism Meter is innaccurate to a degree and your actual mileage is lower than what the screen tells you.

Toyota lie about their MPG's? No!

 

[1000MPH]

Mine's pretty accurate. Over the last 16,265 miles it's .31mpg high. 45psi does seem a little high but I bet your tires will wear more evenly than at spec. I ride mine at 37-39 and the last set still wore the shoulders out first.
BTW, preliminary results of my new Revos are -1.2mpg . The discrepancy between the computer and hand clacs were way off on my last trip. I hope everything evens out in time.

New Revos:
MPG CompMPG Difference
19.68	19.30	0.38
21.91	23.00	-1.09
22.85	21.70	1.15
21.79	22.40	-0.61
25.58	24.80	0.78

 

[nevada]

The tech who did the PDI (Pre-Delivery Inspection) Did NOT air down the tires properly.

45Psi is about the maximum for most P-Rated tires, you'll see a reduced traction pattern, tread life, and such... this goes back to "those people" (the Prius twits) who like to inflate their tires to bursting to get that extra MPG, while spending $$$ for a new set of tires in 30k and swearing they're not losing money...

Anyways, main point is, tire is over inflated; possible wear and safety issues are present. One more thing, Toyota's Optimism Meter is innaccurate to a degree and your actual mileage is lower than what the screen tells you.

the 2013 comes with P tires?


i think most people run around with underinflated tires. i also think(most of) the manufacturer suggested numbers are too low.

 

[1engineer]

the 2013 comes with P tires?


i think most people run around with underinflated tires. i also think(most of) the manufacturer suggested numbers are too low.

So did the '10-'11-'12 models.

 

[<<<<]

I keep my 285's at 30 psi because at recomended 32 it feels too stiff and tread contact is not all the way across on Nitto TG. Any suggestions?

 

[JayceeP]

Mine's pretty accurate. Over the last 16,265 miles it's .31mpg high. 45psi does seem a little high but I bet your tires will wear more evenly than at spec. I ride mine at 37-39 and the last set still wore the shoulders out first.

Do you do a lot of city driving/windy roads? I feel like for those who do, you could get away with over inflating as your outer treads would be more prone to wear anyway.

 

[BlackWorksInc]

Your outer edge will always wear out faster, even more so if you are a manica like me and take turns without slowing down to a crawl, its just the nature of the beast.

All Toyota Trucks and SUVs (and CUVs, but who gives a crap about those...) come with P-Rated tires. Only the "TRD Package" (the imitation bead lock rims) come with LT Tires, which require more air pressure than P-Rated tires.

I also believe that the Toyota specs are far too soft (I believe its mostly to maintain a "softer ride" than anything significant) I found for my 4th gen when I had P-Rated tires 36psi was a nice compromise between firmness and comfort and gave good traction in most conditions while maintaining good wear. Its what I fill all my customer's truck and SUV tires to. The 5th gen is only slightly more porky than the 4th gen, so I'd still run 36psi in the tires.

I also am hesitant to run tires so close to/at their maximum fill spec, I haven't seen or had a tire blow out; but I don't like to push my luck that much as I have seen Commercial Truck tires explode and do damage first hand.

<<<< 30psi sounds pretty low and underinflated for those tires, I'm surprised that 32psi feels that stiff. I'm not trying to put you down, but are you sure you're not just imagining it; sort of princess and the pea type deal? I run Nitto Terra Grappler LT285/70R17's on my 4th gen with a OLW 2.5" Lift and at 46psi, my ride is actually a nice combo between soft enough that I don't feel every pebble in the road like a boulder and firm enough I feel I am gripping the road. I also have a good solid contact patch with the tires. You may be feeling the "firmness" from the shoulders on the tire which are more pronounced than most AT tires.