Check Your Spare Tire Pressure

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Occupied Calif.
:
2019 CX 5 GT-R
I check the tire pressures and give them a quick inspection for things like nails in the treads every couple of weeks. It had been a while since I checked the pressure in the spare though. It is a PITA to check as since the valve stem points down, you have to pull the spare from the trunk to put a gauge on it.
Mine read 45 lbs, it should have been 60 lbs.

I have a bicycle pump that I use to ad a few pounds as necessary to the running tires but that wasn't going to cut it to top off the spare. I remembered seeing a review on YouTube done by Project Farm for tire inflators. I didn't want a 12V model that plugged into one of the sockets on the car so I went to Home Depot and bought this sucker which had received high marks in the review:


The drawbacks are that the power cord is very short so you will need a 3 prong grounded extension cord, and the air hose is also very short. That was no problem to fill the spare but if you want to fill the tires that are mounted you may need to move the vehicle a few feet back or forth to make sure the valve is at the bottom. But for $22.97 I can't complain. It only took a few minutes to go from 45 to 60 lbs and the pressure gauge on the inflator was accurate within a couple of pounds when checked against my ANSI Certified tire pressure gauge.

By the way after buying a certified gauge I found out that the gauge that I have kept in my vehicles for almost 20 years was reading 2 lbs high. Here is the gauge that I now use:

https://www.amazon.com/dp/ (commissions earned)
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I check the tire pressures and give them a quick inspection for things like nails in the treads every couple of weeks. It had been a while since I checked the pressure in the spare though. It is a PITA to check as since the valve stem points down, you have to pull the spare from the trunk to put a gauge on it.
Mine read 45 lbs, it should have been 60 lbs.

I have a bicycle pump that I use to ad a few pounds as necessary to the running tires but that wasn't going to cut it to top off the spare. I remembered seeing a review on YouTube done by Project Farm for tire inflators. I didn't want a 12V model that plugged into one of the sockets on the car so I went to Home Depot and bought this sucker which had received high marks in the review:


The drawbacks are that the power cord is very short so you will need a 3 prong grounded extension cord, and the air hose is also very short. That was no problem to fill the spare but if you want to fill the tires that are mounted you may need to move the vehicle a few feet back or forth to make sure the valve is at the bottom. But for $22.97 I can't complain. It only took a few minutes to go from 45 to 60 lbs and the pressure gauge on the inflator was accurate within a couple of pounds when checked against my ANSI Certified tire pressure gauge.

By the way after buying a certified gauge I found out that the gauge that I have kept in my vehicles for almost 20 years was reading 2 lbs high. Here is the gauge that I now use:

https://www.amazon.com/dp/ (commissions earned)
Whenever possible, I’ve been trying to remind people checking the tire pressure on the spare. ~40 psi on the spare is pretty normal from a new CX-5 you just drove home after all the new vehicle prep by the dealer, to any time you check the pressure on the spare.

Actually you can use bicycle pump to pump up your mini spare from 45 to 60 psi without too many strokes as the volume is much smaller than those road tires. Pump it ~100 times and you should get 60 psi on your spare, and you have got some exercise too. Done it before myself ⋯ ;)

I use a 40-year-old AC Delco / Interdynamics inflator using 120V AC to top off the tire pressure. Onetime I used friend’s Bon-Aire fast inflator which impressed me as it inflates the tire much faster even if it uses 12V DC. It has 2 cylinders instead of one on compressor which makes the inflation twice faster. Pressure release is very convenient too.

Like you, I found many tire gauges are inaccurate and I invested a good one with analog needle from Bosch Germany years ago. But I feel the digital tire gauge is much easier to read, and they’re very accurate nowadays. Those with pressure release is nice to adjust for accurate tire pressure.
 
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2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
I break the spare tire out once a year (no flats yet in this car) when it's time to rotate my wheels on the CX. I can certainly do the job with jack stands and not use the spare but I like to get the spare out and check the air pressure and clean out and inspect the spare tire area. Using the spare to rotate the wheels makes short work of the job.

I also take this opportunity to wash and wax all four wheels, insides and outs. Speaking of which, it's time to do this fun task.
 
:
2020 CX5 Signature
Whenever possible, I’ve been trying to remind people checking the tire pressure on the spare. ~40 psi on the spare is pretty normal from a new CX-5 you just drove home after all the new vehicle prep by the dealer, to any time you check the pressure on the spare.
A few days ago I took off the winter wheels/tires and put on the summer wheels/tires and remembering your advice to check the pressure on the spare I did so. It was at 50 psi and hadn't been checked since I purchase the CX-5 Signature new at the beginning of last August. Thanks for the reminder!
 
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2017 Mazda CX-5 GT, 2016 Mazda6 iGT, 2014 Mazda3 sGT hatchback
With my previous CX9 ('08), once I got a flat at the right rear corner.
I grabbed the spare out only to find that it was under inflated.
Put it on anyway, and drove home since I was 1-mile from home. In my garage, I checked the pressure... <40psi (after 4 yrs untouched). While I was driving it, I could feel that the rear axle was not happy about the difference in diameters... left to right... I drove home very slowly w/ blinkers on.

Lesson learned. Check the spare tire pressure at least once a yr.
 
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2019 Mazda CX-5 GT Reserve
Lesson learned. Check the spare tire pressure at least once a yr.
I'm guilty. And for the couple of minutes it might actually take it's one of those no excuse scenarios. I've just been fortunate that the once or twice I needed the grossly underinflated spare (on other cars, never on my CX-5) I was at home and able to remedy the problem.

That's one of the things I've liked about the VW's I've had. Up until my last one, they all came with a full size spare.
 
:
Occupied Calif.
:
2019 CX 5 GT-R
The other thing you have to remember is that the donut spare is only supposed to be used on the front/driving wheels.
That means if you get a flat on one of the rear wheels, you have to jack up the car, pull one of the front wheels, put the donut spare in its place, jack up the rear, pull the flat off, put the wheel that was on the front in its place and then stow the flat in the cargo area.

I'll bet that would be fun trying to do on the freeway shoulder or in driving rain or snow,
I would only attempt that procedure if roadside assistance was unavailable.
 
:
2018 CX-5 GT
The other thing you have to remember is that the donut spare is only supposed to be used on the front/driving wheels.
That's not correct. From the 2018 CX-5 owners manual:
"Do not install the temporary spare tire on the front wheels (driving wheels): Driving with the temporary spare tire on one of the front driving wheels is dangerous. Handling will be affected. You could lose control of the vehicle, especially on ice or snow bound roads, and have an accident. Move a regular tire to the front wheel and install the temporary spare tire to the rear."
 
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2016.5 CX-5 GT AWD titanium/black 2016 Miata Club ST MT white
The other thing you have to remember is that the donut spare is only supposed to be used on the front/driving rear wheels.
That means if you get a flat on one of the rear front wheels, you have to jack up the car, pull one of the front rear wheels, put the donut spare in its place, jack up the rear front, pull the flat off, put the wheel that was on the front rear in its place and then stow the flat in the cargo area.

I'll bet that would be fun trying to do on the freeway shoulder or in driving rain or snow,
I would only attempt that procedure if roadside assistance was unavailable.

FIFY (fixed it for you)

As Mulligan stated, you have it exactly 100% wrong. The spare is to be used on the rear wheels ONLY.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
FIFY (fixed it for you)

As Mulligan stated, you have it exactly 100% wrong. The spare is to be used on the rear wheels ONLY.
And I agree with everything he said other than this part he put it wrong.

And be aware that the factory compact spare comes with CX-5 2.5T won’t even fit for the front due to the bigger dual-piston front brake calipers!
 
:
Pueblo county CO
:
CX-5 Sport 16.5 6M
Why can't they figure out a way for the valve stem to be reached without removing the spare?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Why can't they figure out a way for the valve stem to be reached without removing the spare?
Mazda needs the space for the sub-woofer on Bose. My 2000 BMW 528i which has a full size alloy wheel as the spare does put outside (the valve stem side) up so that I don’t have to remove the spare to check the air pressure.
 
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Chicagoland
:
2019 CX-5 GT-R
By the way after buying a certified gauge I found out that the gauge that I have kept in my vehicles for almost 20 years was reading 2 lbs high. Here is the gauge that I now use:
Does is come with a certificate of calibration? $15 seems awfully cheap for a calibrated gauge.
 
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Occupied Calif.
:
2019 CX 5 GT-R
Thanks for correcting my post. That's what I get for posting before my first cup of coffee. It does seem odd through, I have owned a couple of other cars, both rear wheel drive, that came with donut spares and there was no restrictions upon using it for either front or rear placements.

The tire gauge that I bought off of Amazon that was described as being ANSI certified did not come with a certificate of calibration. I bought two of them, one to keep in the car and the other for the garage. Both read the exact same PSI which was 2 lbs lower than my old dial gauge. The new gauge also read the same as the gauge that is built into my Husky tire inflator.

So I figure the odds are pretty good that the Amazon gauges are accurate enough. Certainly a lot better than the old pencil gauge that graced my glovebox for most of the 1970's and 1980's.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Thanks for correcting my post. That's what I get for posting before my first cup of coffee. It does seem odd through, I have owned a couple of other cars, both rear wheel drive, that came with donut spares and there was no restrictions upon using it for either front or rear placements.
I do agree with you that it’d be more dangerous to change the tire TWICE on freeway shoulder especially with 18 wheelers passing by! Been there and done that when I had blow-out from my Michelin tire twice on my previous VW Vanagon! I’d just put the compact spare on to wherever the flat tire is, front or rear, and drive the car way with caution and under 55 mph to the nearest tire repair shop.
 
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Occupied Calif.
:
2019 CX 5 GT-R
I do agree with you that it’d be more dangerous to change the tire TWICE on freeway shoulder especially with 18 wheelers passing by! Been there and done that when I had blow-out from my Michelin tire twice on my previous VW Vanagon! I’d just put the compact spare on to wherever the flat tire is, front or rear, and drive the car way with caution and under 55 mph to the nearest tire repair shop.
Or at least drive it to the closest, safe place to change it, like a paved, level parking lot or similar spot.
 

sugob

2021 CX-5 Signature (US)
One thing I was disappointed about was the CX-5 not having a page on the instrument cluster showing individual tire pressures [each as a figure in psi]. Was useful when I had a slow flat on a rental car as could see the figure descending until it got to ~22/23 psi and then the warning coming on [showing the correct tire that was low]. May also be useful to easily see when a tire is down a few psi to prompt further investigation.

Though I don't think the rental showed the psi on the spare.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
One thing I was disappointed about was the CX-5 not having a page on the instrument cluster showing individual tire pressures [each as a figure in psi]. Was useful when I had a slow flat on a rental car as could see the figure descending until it got to ~22/23 psi and then the warning coming on [showing the correct tire that was low]. May also be useful to easily see when a tire is down a few psi to prompt further investigation.

Though I don't think the rental showed the psi on the spare.
Yep, something like this found on Nissan Rogue would be nice!

4A527BDE-A743-4BE5-95CA-1EF9F53D0AEC.jpeg
 

sugob

2021 CX-5 Signature (US)
Yep, something like this found on Nissan Rogue would be nice!

View attachment 297687
Yea, that's nice especially as it shows the recommended numbers [if I'm correctly assuming that's what the blue 35 vals are] and also the units 'psi'. I believe the car system [TPMS] already knows the pressure in each tyre [inorder for it to know when to put the low pressure indicator light on] so it doesn't seem like a difficult/expensive feature to add in future years [more surprising it isn't there already considering I've had it in a few cheapish rentals - in my case I think it was a ford ecosport which was neither sporty nor economical!]
Anyway, what's with the pressures showing - 20 & 15?
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
⋯ Anyway, what's with the pressures showing - 20 & 15?
Yes, 35’s in blue are recommended tire pressure (front and rear, only for factory tires). 20 in amber, and 15 in red simply show this psi (or kPa in metric) tire pressure display has color warning capability (amber - warning、red - caution etc.) on purpose.