How to install an 18 inch spare wheel in a Mazda CX-3
Installing an 18 inch spare wheel in a Mazda CX-3, along with the Bose subwoofer.
In the U.K., Mazda provide a tyre repair kit which is comprised of a bottle of liquid sealant, a valve tool and a 12v compressor. There is an official spare wheel kit available at extra cost, which is a 16″ steel space-saver wheel & tyre, with pertinent accessories.
I’m not a fan of the emergency repair kit. It’s only designed to repair tyres that have a small foreign object stuck in the tread portion of the tyre. To use it, you have to deflate the tyre, extract the valve core, pour in the sealant, reinsert the valve core and re-inflate the tyre and hope for the best. You can’t get the hole repaired later by a tyre specialist, you have to replace the tyre.
The space-saver wheel & tyre isn’t ideal either. You’re advised not to use it on the front axle, you have to stick to a maximum of 50mph, and only use it for a very short distance.
I have therefore fitted an 18″ alloy wheel with tyre in the boot as a spare. The same type of wheel and tyre as the other four on the car. These are the parts I used:
Mazda part numbers and descriptions (purchased from parts department of authorised Mazda dealer):
- 99652-77080 Alloy Wheel 18″
- B001-56-170C Bolt, Jack Set (Holds the scissor jack into the car)
- C236-37-790B Jack
- LD47-37-770 Lever, Jack (This part was already included with the car)
- LD47-69-671 Box, Extension (Wheel nut wrench & jack handle)
- EG21-56-135 Insulator (Circular mat under the wheel)
- DB3P-68-8F1A Board (L), Trunk (Expanded polystyrene moulding left-hand side)
- DB3P-68-8E1A Board (R), Trunk (Expanded polystyrene moulding right-hand side)
- Toyo 215/50/R18 Proxes R40A 92VR Tyre, Valve & Balancing (From local independent tyre shop)
- M8 Stainless Steel Coupling Nut (From Screwfix)
- M8 Threaded Rod (From Screwfix & cut to length with a hacksaw)
- Drop of Thread Lock or epoxy glue
Remove the luggage board and mat from the boot.
Using the wheel nut wrench or other 21mm socket, remove the central bolt holding the Bose subwoofer in place.
Uncouple the connector on the subwoofer cable by squeezing the tab firmly and pulling apart.
Remove the subwoofer from the boot.
Remove the expanded polystyrene pieces from the boot (these will be replaced with new ones).
Remove the cover from the right-hand side of the boot space and install the scissor jack with the jack bolt as per instructions in the vehicle owner’s manual. Replace the cover.
Lay the insulator mat in the boot.
Because the full-size wheel is deeper than a space-saver wheel, the original mounting bolt is too short. I increased it’s overall length to 200mm by adding an M8 threaded nut and a short length of M8 threaded rod, held in place by a drop of thread lock.
Place the new spare wheel into the boot with the outside face of the wheel against the insulator mat.
Feed the subwoofer cable under the tyre and up through a gap between the wheel spokes.
Put the subwoofer into the spare wheel and recouple the cable connector.
Align the subwoofer so that it’s handle is facing the rear of the car. Then put the central clamp bolt in place and tighten.
Place the new expanded polystyrene pieces around the spare wheel.
Put the towing eyes, jack lever, wheel wrench & locking wheel nut key into the cut-outs in the pieces around the spare wheel.
Replace the luggage mat and luggage board.
Because a full size wheel is deeper than a space-saver wheel, you lose the ability to drop the luggage board to its lower position.