I don't think lug nuts or log bolts change the holes on the rim, but I will double check that.

modern spare is not enough, Its still a donut spare that is only rated for 50 miles and 50 MPH.

 

the Modern Spare tire is a Donut spare and it is not rated to go more the 50 MPH and 50 miles. Its not much better then your run flats. The only difference is if you put on the modern spare, you wont destroy your run flat and you may be able to repair it.

 

I'm still shooting for a full size rim (Junkyard) and a tire to use when I go on long road trips.
I am almost positive that the 20 inch Lexus rims from the RX in the last 5 years will work. I am double checking that info.

 

Just found this on ModernSpare website under Gallery/FAQs:

How far and how fast can I drive on a Modern Spare?

Speed

Modern Spare equips all spare kits with tires designated for “temporary use”. In line with our goal of creating a vastly improved spare tire, these radial tires are rugged and reinforced with a well-designed tread pattern. Going a step further, we specifically choose tires with a DOT “M” speed rating. This M rating indicates the tire has been tested to safely operate at constant speeds up to 81 mph. Although it is rated at 81MPH, Many tire manufacturers will state the speed should not exceed 50mph due to the tire’s narrow size. Simply put, the narrow size of the tire (which is designed to save space) may result in a braking and handling difference compared to your normal factory tire. For that reason, when the spare is mounted, drive your vehicle with caution in mind and with good judgment. The DOT M speed rating is beneficial in situations of heavy, fast-moving freeway traffic that may require faster speeds. At times staying at equal speeds with heavy traffic is needed until you can safely exit a congested freeway. It is always best to drive with caution under such conditions and use your best judgment to stay safe.

Range

Typical spare tires, once provided by the carmakers, had range limits of 50 miles or less. This is primarily due to the small size of the spare relative to your factory tires. The 50-mile limit was considered a safe distance to avoid putting undue strain on the vehicle’s running gear. As vehicles have become more sophisticated, many newer models are less tolerant of tire size differences. Just one of our many design goals here at Modern Spare, we set out to build spare tire kits that are still space-saving but are also more compatible with your vehicle’s drivetrain. By having a spare tire size that is closer and more properly matched to your factory tire’s diameter, you can travel farther than the typical 50-mile range limit. If your Modern Spare is not exactly matched to the overall diameter of your factory tires, rest assured we have sized the spare with careful consideration for an allowable size variance of your particular model. Although we do not state a specific range limit, you will find the Modern Spare to be significantly more capable than traditional spare tires. Just as with speed, this very modern setup is not meant to replace your factory tires, rather, is designed to get you safely home or to the repair facility you choose without the stress of a 50-mile rangelimit.

 

I'm not completely sure it is classified a "Donut Spare". I say that because their spare is a specifically designed spare tire more closely matching the factory tire dimensions compared to a traditional spare, reducing strain on the drive- train and extending the usable range past the usual 50 mile limit. The response to the question in their FAQs states that the 50 MPH is considered a safe speed. But in times of need the spare can be driven up to 81 MPH.

But I totally understand what you are saying. There is nothing like having a real tire that matches your daily tires. But the cost and size will definitely bog you down when it comes to space. You saw the photo I pasted of the Modern Spare in my cargo area with the measurements. There is not a lot of additional room once you get that thing in there. I can only imagine how little room there would be with a full size spare. We went on a week trip to Daytona Beach. I could NOT put the Modern Spare and a cooler in the back of my NX with the back seat up. Had I lowered it, yes, there would have been enough room.

 

The previous gen RX uses lug nuts, so you'd need to find lug bolts that match the same seat shape of the RX wheels and also have the same thread length and size as the NX ones.

It looks like you have the F Sport, so why not just buy the identical wheel on ebay and the same run flat tire to make your life easier?

And have you tried taking off one of your wheels and putting it in the trunk to make sure it will fit?

 

Would the hood be strong enough?

 

double check all you want but NO other Lexus wheel will work on the 22,23,24 NX because it is the ONLY Lexus that uses lug bolts with a conical seat.
The Modern Spare is a DONUT tire mounted on a real nice wheel, the tire they use for the 20 inch wheels is a 155/90 18 with 5/32 thread depth-----------------50 miles and max 50 MPH. All things considered a "donut spare" is all that is/has been supplied with cars and SUVs for years. When is the last time you saw a full size spare in anything other than a truck?
As far as getting a run flat repaired you can forget that, tire shops won't touch them and good luck finding a 235/50 20 RF at any shop.

 

Either those wheels, or any others of the correct size with $25 of different lug bolts, available at lexus dealers, tire shops, amazon, ebay, etc. Modern spare comes with the correct set for their wheel.