[Phil75]

The wheel lug nuts are 21mm in size. Using a lug wrench like the one supplied with the vehicle can involve a lot of short throws and resetting the wrench. Once initially broken loose, removing the lug nuts the rest of the way could be much easier with a ratchet, even a 20 volt battery powered driver, and a 21mm deep well socket, six-sided, if possible. The lug wrench is also used to crank the spare tire up and down.

 

[JMII]

Use one of these: https://www.amazon.com/dp/B017MXJHL0/ to protect your wheels. Deep and six sided... designed specifically for wheel lugs.

 

[Phil75]

There is an adapter tube for making the connection between the hex head inside the bumper to lower the spare and the lug wrench. The inner hex head fits a 12mm socket. A 12mm socket and a longer extension would work for cranking down the spare tire, which is a doughnut tire. The valve stem is on the upward side and hidden from access. I expect it would be good to lower the spare once or twice a year and restore the proper air pressure in it so the spare has enough air to get you home if you have a flat on the road.

 

[Spiff]

I turned my spare upside down. I don't see it causing any issues (little harder to put on the hoist), but now I can check and adjust air pressure periodically a little easier. Since I'll spend more time checking the pressure than changing a flat (ideally) this should work well.

 

[Cruz N.C.]

21mm works on the lugs, but has a little play. 13/16, 6 sided is perfect with no movement.

 

[Phil75]

I assumed since most bolts on a Hyundai are metric in size the tire lugs would be also. Perhaps 13/16 inch was chosen is because it is so close to 21mm. Many are now using 3-piece razors as an alternative to cartridge razors. The 3-piece razor invented by King Gillette in 1907 used #10-32 studs. European and Pacific Rim razors are M5 x .8, which is close enough to be interchangeable.

 

[Bossbeard555]

Same company also makes 13/16 non marring.

Just ordered so I can check on Thursday or Friday when it arrives. ARES 59007-13/16-Inch 1/2-Inch Drive Non-Marring Impact Lug Nut Socket - Protective Sleeve Prevents Damage to Custom Rims & Lug Nuts - Color Coded & Laser Etched for Easy Identification

 

[Cruz N.C.]

Don't get me wrong, the 21mm works, but a bit of wiggle can mar the sharp edge of the lug nut. The 13/16 is snug, rub a bit of w-d or a light grease inside to slick it up. This is same size on one of my other cars so I had the socket. Another trick is to wrap the socket with electrical tape, this will protect the rims.

 

[Bossbeard555]

Same company also makes 13/16 non marring.

Just ordered so I can check on Thursday or Friday when it arrives. ARES 59007-13/16-Inch 1/2-Inch Drive Non-Marring Impact Lug Nut Socket - Protective Sleeve Prevents Damage to Custom Rims & Lug Nuts - Color Coded & Laser Etched for Easy Identification

Received the order and this one fit perfectly so would recommend. Will hit it up with some grease like Cruz N.C suggested.

 

[HSC4ME]

I went with one of THESE that works for my aftermarket 19mm black lug nuts and the stock 21mm lug nuts. Also picked up a sliding handle 1/2" lug bar. It fits perfectly in the existing jack cradle.