This guide is for both 250PS and 275PS (Performance) models.
TPMS Sensors (Tyre Pressure Monitoring System) part number: 52934 F2000 (nuts) and 52933 F2000 (sensors)
Locking wheel nuts & key (medium): 99490ADE50
Hyundai officially recommends:
Wheels: 7,5Jx18 ET49.5/50 CB67.1
Tyres: 225/40R18 92V M+S XL
Brand/Model: Hankook W320 Winter i*cept evo2
Why narrower tyres in winter? -Contact patch of a narrow tire is longer (in the direction of vehicle travel) and narrower laterally. This helps the tire break through a layer of snow, slush or water when driving on highways. The longer contact patch must keep the weight of the vehicle over any given point longer, which pushes the tire down more and squeezes snow or water out better. Rain tires used on race cars are often narrower than dry tires, for the same reason. When driving on the street in light snow or slush, narrow tires break through the snow and water down to the pavement underneath. If the tires can engage the pavement, the vehicle gets much more grip compared to engaging snow, slush or water.
So far, as of 08/2018, these 4 tyres seem to be quite popular among tests and reviews:
Michelin Pilot Alpin PA4 225/40 R18 92W XL
Nokian WR D4 225/40 R18 92V XL
Continental WinterContact TS 850P 225/40 R18 92V XL
Hankook i*cept evo² (W320) 225/40 R18 92V XL

Also, for those using a website configurator, you can use i40 as a selected vehicle, because for some reason most configurators show only 19" wheels for the Performance model.
Dimensional Tolerance for aftermarket wheels:
7,5Jx18
ET40 - ET55
5x114,3
Center Bore: 67.1mm (*or bigger with spigot rings)
*Spigot rings are needed to eliminate any wheel wobble, or vibrations that may occur from aftermarket wheels not being mounted centrally onto the vehicles hub. Not using spigot rings is potentially dangerous as the weight of the vehicle will be on the studs/bolts and they could break when driving leading to a wheel coming off!
Finally here are some example of wheels that fit perfectly under official recommendation:
i30 N (250PS)
Part Number: 52910S0000PAC

Hyundai Magnit (in DE Accessories)
Silver & Black

Hyundai Mentari (in DE Accessories)
Silver

Alutec Singa Silver

Mak Wolf Matt Titan

Rial Kodiak Graphite or Polar Silver

BROCK / RC RC26 Titan Metallic

Brock RC B32 Matt Black

Brock B39 HGM *ET50

And some that are not so "official" but nonetheless a very good fit (and visually pleasant):
MSW 86 Full Silver *ET45

MSW 28 Matt Dark Grey *ET45

OZ Superturismo LM *ET48 *CB75
Matt Race Silver & Matt Graphite

Oxxo Vapor Highgloss *ET45 *CB72,6

TPMS Sensors (Tyre Pressure Monitoring System) part number: 52934 F2000 (nuts) and 52933 F2000 (sensors)
Locking wheel nuts & key (medium): 99490ADE50
Hyundai officially recommends:
Wheels: 7,5Jx18 ET49.5/50 CB67.1
Tyres: 225/40R18 92V M+S XL
Brand/Model: Hankook W320 Winter i*cept evo2
Why narrower tyres in winter? -Contact patch of a narrow tire is longer (in the direction of vehicle travel) and narrower laterally. This helps the tire break through a layer of snow, slush or water when driving on highways. The longer contact patch must keep the weight of the vehicle over any given point longer, which pushes the tire down more and squeezes snow or water out better. Rain tires used on race cars are often narrower than dry tires, for the same reason. When driving on the street in light snow or slush, narrow tires break through the snow and water down to the pavement underneath. If the tires can engage the pavement, the vehicle gets much more grip compared to engaging snow, slush or water.
So far, as of 08/2018, these 4 tyres seem to be quite popular among tests and reviews:
Michelin Pilot Alpin PA4 225/40 R18 92W XL
Nokian WR D4 225/40 R18 92V XL
Continental WinterContact TS 850P 225/40 R18 92V XL
Hankook i*cept evo² (W320) 225/40 R18 92V XL
Also, for those using a website configurator, you can use i40 as a selected vehicle, because for some reason most configurators show only 19" wheels for the Performance model.
Dimensional Tolerance for aftermarket wheels:
7,5Jx18
ET40 - ET55
5x114,3
Center Bore: 67.1mm (*or bigger with spigot rings)
*Spigot rings are needed to eliminate any wheel wobble, or vibrations that may occur from aftermarket wheels not being mounted centrally onto the vehicles hub. Not using spigot rings is potentially dangerous as the weight of the vehicle will be on the studs/bolts and they could break when driving leading to a wheel coming off!
Finally here are some example of wheels that fit perfectly under official recommendation:
i30 N (250PS)
Part Number: 52910S0000PAC

Hyundai Magnit (in DE Accessories)
Silver & Black

Hyundai Mentari (in DE Accessories)
Silver

Alutec Singa Silver

Mak Wolf Matt Titan

Rial Kodiak Graphite or Polar Silver

BROCK / RC RC26 Titan Metallic

Brock RC B32 Matt Black

Brock B39 HGM *ET50
And some that are not so "official" but nonetheless a very good fit (and visually pleasant):
MSW 86 Full Silver *ET45

MSW 28 Matt Dark Grey *ET45

OZ Superturismo LM *ET48 *CB75
Matt Race Silver & Matt Graphite
Oxxo Vapor Highgloss *ET45 *CB72,6