Why does tire pressure depend on style of spare tire?

Interesting - was it you that has a FULL SIZED spare?

1. The first thought is a cynical thought - I've read that you're more likely to have a puncture if you've got low pressure - so maybe they bump the pressure if they don't give you a spare so you're less likely to have a puncture;
2. OR - maybe the different weight balance without a spare means you need different pressure?

 

Perhaps @Tideland Prius has some additional insight.

 

That eliminates my answer 2) - so back to my cynical 1)?

 

USA Models have greater range - including 2 different models??


AND

 

I think the difference is due to the awful tire sealant garbage for the Prius w/o a spare. Possibly, the tire sealant only works at lower pressures. Anything greater than the listed pressure, degrades the tire sealant from working well???

2016 models: Two, Three
Have the spare tire, 195/65R15 normal outside tires

2016 models: Two Eco, Four
Have the flat repair kit, 195/65R15 normal outside tires

 

USA 2016 Prius has 6 models (different weights and handling characteristics):

Two
Two Eco
Three
Three Touring
Four
Four Touring​

The tires listed in the chart show different load ratings and speed ratings, which makes sense.
89S = load index of 89 (1279 pounds of weight the one tire can support), speed rating S (112MPH, max speed)
Different air pressures probably due to the vehicle the tire will ultimately be on.

91H = load index of 91 (1356 pounds of weight the one tire can support), speed rating H (130MPH, max speed)
Most likely the Touring tire due to the higher maximum speed, and the fact both Tourings are the heaviest of 2016 Prius, and both identical in weight (3080 lbs).

 

The US Two ECO has no spare & the higher pressures. Higher pressures give better mpg and the Two ECO has a higher rating that the other trim models. The ECO uses the same tires as the other trims with 15" wheels.

 

Yes interesting.
All I can think is lower pressure gives softer ride, and higher pressure is for MPG ratings.

But (pending someone doing some test track runs) pressure change of the small amount is not big MPG factor in theory. Possibly although the pressure effect on a given brand tire is not a big MPG deal, possibly there are different OEM brand tires and different pressure on the higher MPG rated cars,

 

The Prius without a full size spare tire probably comes with run-flat tires. That would be my guess.