Tire Pressure from Dealer @ 50 Lbs ????

50 is bit too high, i had mine set by the dealer 36psi all four tires , and it should be 39 psi (front) 36 psi (rear) for Eco model.

 

I used to run our 17's in the low to mid 40's, just endured the harsh ride. Then just for giggles dropped it to around 36, then 34, and saw near negligible change in mpg, so stayed with the lower pressures. It is easier on the suspension, and less jarring.

 

Too high... for... what, exactly?
There is what is recommended, but you are free to set it at whatever you like.
Some people like/prefer 50.

 

Agreed.
They should set it at what you want.

Lowering your tire pressure would not have improved your mpg.

"seemed to handle better"... That's where it's hard to quantify.

 

The first thing I did after I got the car home was to increase the tp to max. sidewall 51psi. Higher tp also improves handling but to each his own.

Toyota put a specific set of tires on the car and recommended a specific pressure. Hope you buy the same tires when it is time to replace them.

 

IMHO, a bit higher (several psi) than the placard is ok, but a 50% higher (50psi v.s. 33psi) is really questionable.
It could cause uneven wear (more center than shoulder), and may hurt stopping distance too (actual number depends on surface condition).

 

It has to stress suspension more.

 

You might need to revisit Toyota 2016 Prius 17" psi recommendation by driver side placard, listed as 32/33 psi but you can do whatever makes you happy.☺

 

I agree, 50 psi with the low profile 17" is just nuts, really hard riding.

 

Tire Pressure Preference is one of those personal actions that create devoted camps of belief.

I've experimented with higher pressures, but if I saw MPG gains? They seemed pretty minimal to me.
What was for sure, was that the higher pressure caused a less stable, jarring ride.

Given a vehicle that has an IMO very aggressive traction control system, coupled with regenerative brakes, I'm going to value "smoother ride", because I think it could translate into also being a "safer ride".

Therefore, I pretty much keep the tires inflated to the PSI recommended in the door jamb. My MPG are fine, and at least I know I'm not stressing the suspension or the traction control system by driving on "economical" but hard tires.

I honestly think the "trick" is to check and maintain.
I get good MPG AT the recommended PSI, but if it falls too far below it? The MPG's then can really suffer. So I check at LEAST 1 a month or every 2 weeks. Keeping in mind that season temperature changes can change the equation.

 

The one thing that we agree on is that the tp should be checked, especially in the winter. 32psi in the shop at 70F won't be 32psi in the parking lot at 20F.

 

Found this pretty dated doc, interesting:

http://www.john2211.nl/Hybride_links_files/Predelivery.pdf

Nothing in my glove box.

 

The 50 psi is the maximum cold pressure of most Standard load ( SL) or XL/reinforced/Extraload tires.
The pressure needed for the maximum load up to maximum speed of tire , or if lower 160km/99m/h, is lower.
Also called maxload-pressure/reference-pressure/ but printed on sidewall sometimes AT yyy psi , so will call it AT-pressure furtheron.
SL tires Eur system AT 36psi/250kPa/2.5barr with exeptions to lower, USA system always AT 35 psi/240kPa.
XL// tires EUR AT 42psi/290kPa with exeptions ( 41/44) , USA system always 41 psi/280 kPa.
On SL and XL// tires only maximum cold pressure is given on sidewall, LT/C(omercial) tires only give AT-pressure on sidewall so are allowed higher pressure then that.

Advice pressure is nowadays for normal use , calculated for Maximum allowed axle-loads ( GAWR/MPAW/MTA) for up to maximum technical car speed, and behind often AT or maximum cold pressure, to cover overloading on rear axle.

before the year 2000 , normal use advice was calculated for axleweights determined by the car maker for 3 persons and a little load , wich gave lower pressure, and often front higher then rear.
And because most only drive with driver and little load, this old advice could still be OK, and then even for maximum used speed of 160km/99m/h.

For fuel saving extreme high pressure does not give that much advantage in compare to calculated pressure for the load , with 10% reserve added to that load, for things like pressure loss in time,incidental extra loading, misreadings of pressure and misyudging of loads, etc.
So you probably can lower the pressure to at most 35 psi if tires are SL.
But best is if you give here the data I need , so I can calculate it for you.

Will give 2 lists for pressure change in relation to temperature change.
One is in degrF/PSI and the other is in degrC/kPa ( 100 kPa= 1 barr=14.5 psi)
How to use it:

find the pressure you measure at the ambiënt temperature at that moment if not exact in the list interpolate.
Cold pressure is simply when inside tire temp = outside tire temp ( ambiënt), and the advice cold pressure is assumed for Ambiënt temp of 18/20degrC/65/68degrF.

Then see what it will be at the ambiënt temp when driving. mostly cold measured in the morning before the tripp when ambiënt temp is lower then in the afternoon when driving.

Assume tiretemp inside to rise about 27degrC/47 degr F when driving about 90km/55m/h.
Add this to the ambiënt temp when driving and look up what the pressure is warm in the list.
Compare that to what ( accurate haha) TMPS gives on the screen, and if its higher , your tires get to hot so cold pressure to low, then highen up the cold pressure.

All an indication because all the data needed are never 100% accurate, and temp rising normal is my conclusion so discussable.

Greatings from a Dutch Pigheaded Self-declared Tire/tyre-pressure-specialist.
Peter

 

I always have the opposite problem. Every time I took the wife's 13V in for complimentary service every 5000 miles, the dealer service techs lower the pressure to 35PSI. I had just gotten used to cranking up the air compressor when I get back. But now that it has over 25k miles, no more complementary service. So the problem is solved. I do it myself.

 

FWIW, my new Rav4 Hybrid came from the dealer with 55PSI in the 235/55R18 tires.

 

Nice!

 

Any recommendations for a "accurate gauge"?

 

I like the Accu-gage brand. The "H" or "S" series.
Can be purchased in many locations including
Tire gauges

 

So, I guess I will betray my massive ignorance here, but hopefully with some understandable context. I have, from time to time, been a cyclist, and I know how important tire pressure is. I never ride my bikes without checking pressure first. I always look at the sidewall and see what the max pressure is and set it right around there. I thought that was how you did it. If the tire said 120 psi, then I set it for about 110.

For some reason, I had the idea that when inflating the tires on my car, I should look at the max tire pressure on the sidewall and inflate to that. I know it says "max" but I thought that was just a figure of speech or something I guess.

I never knew to look inside the door wall. But, now I have to wonder, how do they know that any tire you put on the car of that size is going to need that psi? Isn't the pressure more determined by the rubber of the tire and its construction? I checked my tires and saw they were at 34 and thought they were massively underinflated. I promptly put them up to 51 since that was what the sidewalls said.

Now I don't know what I should be doing.