Tuesday, January 7, 2020

DIY Spare Tire Kit for a Little Peace of Mind

The spare tire is a controversial topic these days. Obviously, the accountants for major auto manufacturers have made this decision for us. Most new sedans don't come equipped with one - even with a temporary compact spare. I'm sure cost, weight, probability of flats, lack of knowledge by owners to change, safety, liability, road-side assistance access, blah, blah, blah, excuses can be given. Ever since I was about 13, my dad taught us to change a flat, because well... $hit happens and it has happened over the years.

Thinking back to the numerous times that I have pulled over (even while on my bicycle) to help clueless drivers change their flat tire makes me sure that I always want one handy for myself.  Personally, I don't want to be stuck on the side of a road in a remote location over a holiday weekend with the family in the car and be completely powerless to do anything, but wait for someone to show up and tow me. So I have always built a spare kit for every vehicle that I have owned, and my Model 3 is no exception.

Luckily with some DIY ingenuity, I was able to re-purpose a kit for my Model 3 using the kit from my previous Infiniti. Having a spare is only the the half of it, knowing how to change it safely is the other half.

Net result, an 18" tire/wheel that matches very closely with my Tesla 19" sized tires, has the adequate weight capacity rating and is an exact fit around the hub and studs. Coupled with that a scissors-jack, lug wrench, jack adapter, lugs and spacer kit.

The keen eyed will noticed that it is balanced and filled with Nitrogen.
DIY 18" Alloy Spare Tire Kit for Model 3- Success!
Of course this kit is not complete without a set of proper spare tire tools to actually be able to change a tire:


Tool kit for changing Model 3 spare tire
My Infiniti kit was a Maxxis T145/70R18 107M on Enkei light weight alloy wheels, nitrogen filled and road force balanced. The specs were 5x114.3 with 40mm offset and M12x1.25, center bore 66.1mm.

My Infiniti Spare Kit that I had built.
So this is DIY project started by checking the full spec and bolt patterns of my Tesla Model 3 which are:

Tire: 235/40ZR19 96W, Rim: 8.5Jx19 ET40, PCD 5x114.3, Center Bore 64.1, Thread Size M14x1.5 
My existing kit had a bolt pattern of 5x114.3, with an offset of 40mm which was the first step to pass so it would clear the calipers and fit the studs. The next step was the thread size, which was M12x1.5. Therefore, I put the wheel on a drill press and expanded all 5 holes by 2mm to fit M14 studs. The tire was in excellent condition thanks to nitrogen fill I maintain on all tires.
Excellent Tire Condition
The next step was to center the wheel on the hub, so I purchased a set of 2 mm hub rings adaptable from 64.1 to 66.1 mm, which ran about $6 for a set of 4. Last step was purchasing M14x1.5 mag seat lugs nuts with the same 21 mm external socket size. These ran about $14 for the set of 5. Lastly was a jack pad to fit the Tesla which was another $10. So the total was about $30 and a little bit of labor to get a spare tire kit build.

Anyways here is the entire procedure.

Safety first. Installed a set of chucks on both sides of the opposite diagonal wheel from one being removed.
Safety first. Chucks on wheel
Removed the Tesla plastic wheel finisher cover by pulling on any two consecutive side.
Remove cover by pulling any two consecutive sides
Loosen the lugs in a star pattern using a breaker bar and not a torque wrench. My 21 mm socket is wrapped in electrical tape not to scratch the wheels.
Loosen lugs in star pattern before jacking
Use the jack adapter in the slot and jacked up the side of the Model 3 using a floor jack.
Using Tesla Jack pad adapter to avoid damaging the car
Removed the lug nuts and the wheels from the Model 3 to make measurements and fitment
Model 3 Jacked up and wheel removed
The modified compact spare wheel, with bored out bolt holes and hub ring spacer installed.
Wheel Modified and ready for Model 3.
Turns out that the calipers and brakes in the Model 3 are pretty heavy and made in Mexico. Surprising with the regen how little the brakes are actually used.
Calipers made in Mexico
The space efficient spare wheel fit like a glove, but Mag or flat face lug nuts were needed as the Model 3 Tesla acorn style lug nuts would not work.
The wheel fit like a glove but needed different lugs.


At this point I put back the original wheel back, tightened the lug nuts and lowered the Model 3 back down and torqued the lugs to 129ft-lb. I did this so I could use the actual spare kit tools to practice changing the wheel using the tools that would be available in case I had a real flat.

So I loosened the lugs using the lug wrench instead of a breaker bar. Jacked up the Car using the scissors jack. By the way the jack needs to be rated to support the weight of the Model 3. In Nissan terms that is a V8 class jack.
Jack up the model 3 using scissors Jack
Once the model 3 was jacked up, the spare wheel was installed, flat head lugs were used to secure the lugs and then Model 3 lowered, then the lugs tightened to what seemed like 120 ft-lb,. Of course knowing that a torque wrench would not be available, it had to be estimated.
Spare Tire installed with lugs torqued.
After that I drove around the block to make sure everything worked well. Two of the items that I was concerned about were: 1. size, and 2. weight.

Regarding size, the tire percentage difference was minimal. Actually better than with the stock Infiniti/Nissan 19" tires @ 83.9", Tesla 19" @ 82.9" and Compact spare @81.6" circumference.
Add caption
The compact spare inflated to the required 60 PSI supports 2,149lb, which is above the stock tires maximum load of support of 1,565 lb.

The spare tired turned upside down does not take up much space in the trunk and the well can be used to hold the jack and remaining kit. As a backup I always carry tire patch kit and 12V pump to be able to repair a tire on the road, but that is a different topic of discussion.

Q.E.D.