2016 Prius Excel - Tyre Pressures for Load & Speed

[Bowruss]

My manual and the door plate info only give one set of pressures.  Anyone know if we should be increasing pressures for fully loaded (my Belgian beer trips) or for sustained speed.

My other and previous cars all had alternative pressures for these differing conditions.

Another case for getting the full manual....

Thanks for any advice/comments.

Russ

 

[PeteB]

If you can download the manual it's on page 667.

It doesn't give any advice for a full load (as you say, previous models did).  It does, however, recommend adding 3 psi all round if towing (oddly, elsewhere it says you can't tow on models sold in some countries and you can in others!).

Another odd thing (to me) is that for cars with 15" wheels it quotes different pressures according to whether the car has a full size spare wheel or not (36/35 F/R without, 32 all round with).

 

[Bowruss]

12 minutes ago, PeteB said:

If you can download the manual it's on page 667.

It doesn't give any advice for a full load (as you say, previous models did).  It does, however, recommend adding 3 psi all round if towing (oddly, elsewhere it says you can't tow on models sold in some countries and you can in others!).

Another odd thing (to me) is that for cars with 15" wheels it quotes different pressures according to whether the car has a full size spare wheel or not (36/35 F/R without, 32 all round with).

 

Thanks for this. 

It is all a bit odd.  So - pressures that are fine for one or two people and no load and no sustained high speed are apparently OK for a blast to Belgium with four up including luggage, a Roof Rack and box and coming back with as much beer as possible (all subject of course to max payload limit) and the whole trip at motorway speeds?

I always thought that you increased your pressures to allow for increased temperatures and stresses due to sustained high speed and load.

Maybe this is all a bit last century as far as my Starship Prius is concerned!  Or perhaps I've missed a button down three or four menu layers which sorts it...hmmm.

I'm getting old.

Russ

[PeteB]

My 2012 Prius predates the fitting of Tyre Pressure Monitoring systems, so I've installed an aftermarket system that displays temperatures as well as individual tyre pressures.  It's given me quite a few surprises.  The biggest influence on tyre pressures is by far sunlight, even weak sunlight.

What really surprised me was the side in strong sunlight can reach 5-10°C above the side in the shade, and the hotter tyres can display a pressure of 3-5 psi above those on the shaded side, which themselves may have risen by 1-2 PSI.

Driving at 70 mph for any length of time seems to only add 2-3°C and 2-3 PSI to the pressure (with 2 people and lots of luggage).

So potentially, up to 10 PSI increase at speed on a hot day, which is another reason I avoid the temptation to over inflate to boost mpg.

[kithmo]

Tyre technology has changed quite a bit over the years, I'd stick with the pressures recommended for the beer run.

[Bowruss]

4 hours ago, kithmo said:

Tyre technology has changed quite a bit over the years, I'd stick with the pressures recommended for the beer run.

Thanks kithmo.  You're probably right.  I think I'm just going to run an extra 1.0 bar all round.

Russ

[Joseph D]

1 hour ago, Bowruss said:

I'm just going to run an extra 1.0 bar all round.

1 bar is 100 kPa (14 PSI). I would think that is a bit excessive.  I'd aim for an increase of 20 - 35 kPa (3 - 5 PSI) all round.

I'd also check the tyre wear every 2500 miles (4000 km) checking for signs of under or over inflation and adjust my tyre pressures accordingly.

[Bowruss]

Hmm...OK - I think  I'll go with the 3-5 psi all round.

Might change again subject to more comments though!

Thanks, Russ