2017 Spare Tire Mod for U.S.

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2019 Mazda CX-5 Signature
Just bought a 2012 CX-7 spare (18x4) for $50 shipped off ebay. So at least I'll have the wheel. I doubt the tire will have much useful life.
 
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2019 Mazda CX-5 Signature
I can't remember ever getting a flat or puncture on the fronts. I always seem to pick-up nails in the right rear. So for me (2019 Sig) it is more an issue of protecting the AWD gearing.
 
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2014 Mazda CX-5 GT AWD w/Tech
I'm sure Mazda's response will be to eliminate the spare and just supply a can of fix-a-flat in the spare tire area!
 

brillo54

Resident Curmudgeon
Contributor
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NE Indiana
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'16 CX-5 GT FWD
They wouldn't be the first to do that. That's all my sister-in law's '16 Jeep has.
 

sm1ke

Work In Progress..
Moderator
Contributor
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Canada
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'18 CX-9 Signature
Ideally you would do as the manual says:

"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."

That said, I can appreciate wanting to get out of that situation quickly. In that case, having a spare that also fits on the front would have been ideal. I suspect that Mazda simply chose not to spend the extra money on a spare that accommodates the front brakes, and intends to fall back on the statement above when questioned.
 
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2018 AWD GT Premium Red/Black
Ideally you would do as the manual says:

"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."

That said, I can appreciate wanting to get out of that situation quickly. In that case, having a spare that also fits on the front would have been ideal. I suspect that Mazda simply chose not to spend the extra money on a spare that accommodates the front brakes, and intends to fall back on the statement above when questioned.

In AWD all wheels are driving wheels.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
Calculation aside, here's the spec of overall diameter from all OE tires used on Mazda CX-5 and supposed T155/90D18 spare for CX-5 AWD. Dunlop Space Miser T155/90D18 113M tire is the spare found in CX-7 AWD and 1st-gen CX-9 AWD. They're all within reasonable 0.4" tolerance on overall tire diameter.

Mazda CX-5 OE TiresSizeOverall Tire Diameter
Yokohama Geolandar G91A225/65R17 100H28.5"
Toyo A23225/55R19 99V28.9"
Yokohama Y870BT145/90D16 106MN/A (26.3" estimated)
Dunlop Space MiserT155/90D18 113M28.5"
I noticed by accident a 18X4 compact spare steel wheel which is supposed to have Dunlop Space Miser MKIII T155/90D18 103M tire from a 2015 Mazda CX-9 is available on LKQ North Texas website. I immediately located and verified the spare tire and model year, and placed an order. It costs $78 but I have to go and get it by myself. It’s at LKQ Kennedale which is 50 miles away from my house. But I’ve been wanting to have a correct-sized compact spare for my 2016 CX-5 AWD, so that I have no worries damaging my AWD system when I actually have to use it. Hence I decided to drive about 3 hours to get a spare from a newest possible Mazda vehicles for the size. I was a little disappointed when I picked it up as the spare had been used for unknown miles instead of “never been used” claimed by the salesman. It’s dirty apparently it’s been exposed to the elements for a while. The date code is “KATP2715” so it’s newer than the date code “ADT4614” on my current Yokohama Y870B T145/90D16 106M compact spare. Like tomcat1446 said earlier, the size difference is huge. And the 18X4 steel wheel with T155/90D18 103M compact tire is a perfect fit in the trunk for our CX-5.

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2019 Mazda CX-5 Signature
I thought my old CX9 (1st gen) had the spare mounted under the cargo area floor pan. So it would of been exposed to some dirt and road grime. Not sure if 2015 was different. Sorry, I no longer remember how it was hung (only needed it once in 11 yrs). The rust and cosmetic blems I see on your 18" might be caused by the hanger's friction. So it is entirely possible it has never been driven on.
 
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2014 & 2019 CX-5 Touring(s)
Yeah - from your pic in the trunk, it looks like the tire mold sprues are still there. They'd be worn off pretty quickly if the tire was used on the road.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
I thought my old CX9 (1st gen) had the spare mounted under the cargo area floor pan. So it would of been exposed to some dirt and road grime. Not sure if 2015 was different. Sorry, I no longer remember how it was hung (only needed it once in 11 yrs). The rust and cosmetic blems I see on your 18" might be caused by the hanger's friction. So it is entirely possible it has never been driven on.
Good to know that the spare tire on gen-1 CX-9 is mounted under the floor pan. That explains why it’s so dirty. I washed it and waxed it and that’s how it looks right now in the pictures.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
Yeah - from your pic in the trunk, it looks like the tire mold sprues are still there. They'd be worn off pretty quickly if the tire was used on the road.
Yes the mold sprues are on the tread surface, but mostly are on the side tread, not on the center tread. Of course there’re scratches and rusts developed around 5 bolt holes of the steel wheel, that’s the hard evidence that this spare had been mounted and used as a road tire.

Nevertheless I’m very happy to get this correct-sized compact spare, and the tire itself is even newer than my original spare. Especially the current price for a new Dunlop Space Miser MKIII T155/90D18 113M is pretty high for $147.47 at the Tire Rack.
 
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Austin, TX
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CX-5, 2019 GTR
Prices for e-bay spares seem to have gone up, but I found a 2017 Sonata wheel with an unused 165/90-17 tire for $105. A little research found recommended replacement for donut spares is 10 years if not used…tire I bought was made 41st week of 2016, so will be due in late 2026, if I do need to use it, I’ll make a judgment then about earlier replacement. Also, road tires will probably be due then as well since I don’t put many miles on it. On my 2019 GTR I cut about 1/2” off the foam spacers with a hacksaw which seems to work fine…floor is flat and solid with my factory rubber mat. I plan to sell the existing spare to a Hyundai or Kia owner. Now I just need to modify the hold down bolt…
 
I hate the idea of having the incorrect diameter tire for the spare, especially when most other countries get a spare that has the correct diameter. Australia, Mexico, and most of Europe get a 185/80R17, which is still a temporary use spare, but it has an outside diameter of 28.7", which is exactly the same as the factory 225/55R19 (the 17" tires are 28.5" which is basically the same thing). In the US, we are given a tiny 145/90/16, which has an outside diameter of 26.3". A difference of 2.4". This small spare will go 68 more revolutions per mile than the stock tires when in use, which would be more important to AWD owners, but I think could also create problems for FWD if you have to put it on the front. Plus it is so damn skinny I don't trust how long this thing could actually hold up if you needed it to. I'm sure Mazda did this to save the 11.6 LB weight difference, but how much fuel can that save really?

You can't get the 185/70R17 tire available in other countries anywhere in the US. I tried a lot of places and you can't. But I did find a 165/90R17 from Tire Rack that also has the perfect diameter of 28.7". This picture shows the factory tire, the new spare from Tire Rack, and the original spare for comparison. Which spare would you rather use if you were in the middle of nowhere?

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Now the best part is that even though it is a much wider and larger diameter tire tire, it will fit in the spare storage area and still keep your floor perfectly flat. Here are pics of the original spare first, and the new, correct size spare second. Bose subwoofer will still fit perfectly.

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The only real "mod" you have to do, besides ordering a new spare wheel and tire, is to remove the foam blocks that Mazda installs in the floor board to make up the space created by giving us this incorrect sized tire. So you simply pull off these 2" thick foam pieces in the picture and the rear floor will rest perfectly on the new wider spare.

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One final pic of new spare vs original spare.

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Parts needed:
17" X 5.5" steel wheel from Med Center Mazda https://www.shopmazdaparts.com/oem-parts/mazda-wheel-spare-9965025570/?c=aT01NDY1MTcwNSZyPWxheWVyXzE= $119.31
T165/90R17 Kumho T121 from Tire Rack https://www.tirerack.com/tires/tire...m=69R7KH&vehicleSearch=false&fromCompare1=yes $79.10
Weight of original spare and tire 24.4 LB. Weight of new spare and wheel 36.0 LB.

You can also use a true factory aluminum wheel and full size tire and it will fit diameter-wise, but the thickness will raise the floor level about 2.5".
Do you think a 235/60r18 would fit? How much would the floor height be raised by? I’m thinking this may be the best way to carry a “full-size” spare instead of roof rack nor hitch tire carrier