Tires size possible deal breaker on 2023 Prius?

i would never replace the spare, never heard of one going bad

 

Every tire has a time limit. Spares last longer than regular tires because they aren't as exposed to the elements or put under load, but they are still pressurized to 60psi for years or a decade or more, and the rubber in the tire still is exposed to air. The last thing you want after you change a flat tire on a rainy night is the spare to blow out a mile later due to dry rot.

A regular tire can start getting hard in as little as five years. Generally seven years is the oldest your regular tires should be(from the date code on the tire, not from when you bought and installed it). Ten to twelve years is the longest I'm willing to go on a spare. Especially since the dry rot might be only be showing on the inside of the tire where you can't see it.

The cost works out to be less than $1 a month over the life of the spare. Worth it in my book.

 

https://www.pajcic.com/case-results/1-spare-tire-3-deaths-1-quadriplegic/
Jury Awards $18 Million in Death of Child Blamed on Aged Tires - ABC News
https://www.hop-law.com/jury-awards-1-38-million-verdict-in-spare-tire-lawsuit-against-discount-tire/
Now you've heard of three.

 

Has anyone confirmed the wheel specs and bolt pattern for the GEN5?

 

Nope

 

I wonder how fast they were going

 

I contacted my go-to place about replacing spare tire (on our 2010); they said they can’t (or won’t) get them. A little frustrating. I’ll maybe ask if I get them one, say through tire rack, if they can mount it.

addendum: they “might” be confused, thinking I need rim as well. Will see.

 

Would you also replace 10 year old airbags? Do you really trust them to work when needed?

 

I’d go with car manufacturers recommendation.

OTOH: There’s pretty much consensus that tires have a lifetime.

 

Distance could have also been a factor. Though a tire a few years old is far less likely to detread under the same conditions than one over a decade old.

Actually, some manufacturers did call for replacing air bags back when they were still new. Decades of data has shown that isn't needed with air bags using glass to metal seals for the charge squib and a working diagnostic system.

Plastic to metal ones end up letting moisture in, and that degrades the propellants and igniters over time. The air bag may not then fully inflate, or go off without cause. I think Honda recently had another 'park the car' order for suspect airbags.

Decades of data shows that tires degrade from exposure to air and light since the moment they are made. Spares are sheltered from light, but not air.

 

There must be tire testing data somewhere, they don’t just make this stuff up, do they?

 

Goes back to at least the '80s. Don't have ready access to full research papers right now, but this slide show cites some of them, plus a couple of those crashes I posted earlier.
https://www.ntsb.gov/news/events/Documents/2014_Tire_Safety_SYM_Panel_4b_Kane.pdf

After the Firestone tire recalls, the NHTSA was tasked with developing new testing and standards for tires. Here is a couple slides summing up progress some results.
https://www.nhtsa.gov/sites/nhtsa.gov/files/0703macisaac.pdf
https://www.ntsb.gov/news/events/Documents/2014_Tire_Safety_SYM_Panel_4a_Soodoo.pdf
Tires that have a 1% or less chance of tread separation at 2 to 3 years of age, can have that chance increase to 5% to 10% in year 5 to 6.

Slide 18 of the second link.
Guidance for Consumers on Service Life Recommendations
• NHTSA does not have its own research data to develop guidelines for consumers on service life recommendations.
• However, the following recommendations, which were included in the Report to Congress, are from several vehicle and tire manufacturers:
 Vehicle manufacturers: Replace your tires after six years regardless of tread
wear; this also applies to your spare tire.
 Tire manufacturers: Recommends that tires be removed from service ten years
after the date of manufacture

 

Is there any good information as to exactly how much the fuel efficiency is affected by having 19" vs 17" tires? The XLE drops 5 mpg off the LE but how much of that is due to the tires vs. other factors?

 

I mentioned 5x100 in a comment a couple weeks ago but somebody corrected me to say it's 5x114.3 (which if true might open up a world of Honda wheels)

 

Space saver tires are *supposed* to be 60psi or thereabouts, but nobody ever checks the pressure regularly.

Any time I've checked the pressure on an "old" space saver it's usually 20-30psi...maybe I'm just unlucky

 

Added features do add weight, and the 19" wheels may increase air drag. This isn't enough to explain the mpg difference in the Camry hybrid and new Prius trims.

It is well known changing wheel and tire weights has a big impact. It isn't just weight the car has to move like cargo. It is weight that saps energy by being jostled on the suspension, and with being spun up.

It's at 60psi long enough to squeeze oxygen into the rubber. That's why tires mounted to a wheel and pressurized are called in service even if they are never put on a car.

 

I recently discovered that both "donuts" (My Prius and My wife's Subaru) were very low. It turned out that the dealers never bothered to check the spare tire pressure. Now when I reset the pressure on my tires (since the dealers tend to set them too soft or my taste), I remember to check the spare. Last time is was just over 50 PSI, not an excessive loss in 6 months and mostly due to the lower temperature in the winter.

JeffD

 

The factory would have set the pressure to the right level. It might even over inflate to compensate for pressure loss, and reduce flat spots forming, during transit. I doubt they'll ignore the spare.

Owners on the other hand, were ignoring the pressure of the regular tires. Which is why we have TPMS in all cars now. Forgeting about the spare is another reason for carrying a pump in the car.

 

I was discussing the dealer behavior, not the factory. The dealers tend to follow the factory suggested PSIs which are a compromise between Comfort. Tread life and MPG. The factory setting emphases comfort. I tend to emphasize the other two and choose a higher PSI (but lees than the MAX COLD rating of the tires). The tires I use are stronger than the OE tires and have a higher max cold psi (51) so upping the pressure to 42(front)and 40(rear) in my Prius is my choice.

I also raise the PSI 5 lbs. higher, reset the TPMS and then lower the PSI to my chosen settings so that the TPMS system will warn me earlier if there is a pressure loss.

JeffD

 

When we purchased our 2010 new at dealership, paying full PDI, spare measured 40 psi. Oh and then there was the dead 12 volt, they tried to mask. This is Open Road Toyota, Port Moody, just giving them a plug.