I have an 2025 NX 250 that came with 18 wheels.
I switched over to 20” sport wheels.
my question would be, does the Psi remain the same? Or should the 20” have more psi.
anyone out there with the original NX sport wheels I would be curious to know what the psi on the side of the inside of your dad reads.

thanks

 

My manual says the same 33 psi. Except if you drive above 100 mph [160 km/h], then you add 3 psi to 18" tires but 6 psi to 20" ones.

 

Thank you

 

Mine came with the 20s (NX 450). They came set at 40psi and after every service they seem to set them up for 40psi. I know you get slightly better mileage with higher PSI so maybe that?

 

did you have any perceptible change in handling for the vehicle?

 

You will get less mpg dur to the increase in tire diameter. There is a lot of discussion about replacing tires that discusses this. Other factors are also harder rider, poorer handling, etc. I would set your tires at the recommended psi for optimum, mpg, handling, and ride comfort. Remember, the NX is a luxury cruiser not a sports car. Enjoy your NX for what it is.

Good Luck.


YMMV,
MidCow3

 

33 PSI as stated on door jamb.
My 350F Sport has 20' wheels and Lexus specs 33 PSI.

 

Thanks but no thanks. I had a prius before this (still have it) and I run higher psi on that too since the start (over 200k miles on that car). You get better mileage and better tire wear with a slightly higher psi so I'm sticking with that. During the first few months of owning that car i was getting higher outer wall wear, but after the slight (~5psi) increase in tire pressure I was getting more even wear and better mileage. And also tires lasting 80k miles. I'll stick with my empirical evidence.

I know the ride is a bit harsher but since it's mostly highway driving and very few potholes/uneven surfaces that isn't a real concern.

 

One wonders what else they're not doing to factory spec.

 

Yeah... but this is over 2 different dealers. I've done 3 services in Boston, MA and two in upstate NY.

 

Just had my 2022 350h in for the 30K mile service. I had new tires put on it the day before. When I picked up the car, the tires were all 36psi. I asked the service guy about it. He said their tire techs have a chart from Lexus they use to set the psi which does not match the 33 psi spec in the manual.

I had the same thing happen with my previous car, an Audi A6. The service department had a chart from Audi which they used to set tire pressure and it did not match the manual spec.

 

I think you should look at the maximum pressure for your particular tire (written on the sidewall by the manufacturer) and inflate to an appropriate percentage of that psi. If your max psi is 50, inflating to 33 psi doesn't make much sense to me (66% max psi). You would probably see a visible bulge on the tire. Something like 36 psi (72%) or 37 psi (74%) makes more sense to me.

 

Higher PSI increase the diameter and that alone would make the mpg less. However, increasing the psi has significant negative effects:

Increasing the PSI reduces the rolling resistance by decreasing the the tire contact patch size. What does this actually mean:
(1) you traction is decreased. If you try to start fast you will spin your tires. This is more apparent in rain or other inclement conditions
(2) your stopping distance will significantly increase, Again, much more apparent in wet or inclement conditions.
(3) your tire wear and total miles per tire life will be decreased ( you are only riding on the center treads; the outer treads get very little wear). Newer tires have significantly longer tire life up to 80,000 miles, so you may erroneously thins increasing PSI is getting you longer tire life. But actually increasing PSI shortened your tire life.
(4) You handling will be deceased. To start with the NX is not a sports cat and does not handle like one. When you increase the PSI you handling is further reduced. This makes it more dangerous in traffic control and wreck avoidance.
(5) You have a much harder and uncomfortable ride.
(6) Finally a positive, , by increasing the PSI you will get 1 or 2 mpg higher.

Recommended PSI is best. But , please don't exceed maximum PSI. Even staying at maximum PSI you get many of the negatives mentions above. However, lower rolling resistance can increase your mpg by 1 or 2 mpg if that is your main goal.

Peace and roll on.

YMMV,
MidCow3


P.S. - on my 2023 Prius LE. I changed tires from OEM 195/60 R17 to 215/55 R17. It increased my rolling resistance and increased my patch size. Much better starting/stopping especially in wet and inclement weather. Increased the handling significantly. However, dropped my mpg down to about 48. But it was worth it. Yes, running tires at recommended PSI

 

Yikes! The dealer had the 20 inch wheels with tire pressure around 47 psi. Max pressure is 51 psi for the tires.
After a short highway drive I brought them down to 42 psi. The door jam says 33 psi.
I think somebody messed up at the dealership.

 

In simple terms here, a pneumatic tire is providing both traction and a cushioning effect to road irregularities ie bumps potholes. Factory recommended pressure is typically found on drivers door B Pillar / Post down towards the bottom. 33 psi 'cold' is the recommended pressure setting. Cold meaning you haven't driven the car in over half hour or so and it's not in bright sunlight. Temperature swings will change the indicated psi as can be seen on your centre screen coming from the individual TPMS sensors. Tires are black in colour, in bright sunlight tires on the side that is exposed to the sun will heat up and pressure will increase about 2 psi or more so be careful.

I had my winter tire swap done mid April here in Niagara Falls Ontario. OE went on and pressure was set at 34 psi - which I'm ok with. That's when it was around 5-7 degrees Celsius (41-45 Fahrenheit). After a few weeks went by the air temps rose to around 16-18 C - 61- 64F, tires were reading 36-38 psi. That's a little too high for me, the ride is a little too stiff and harsh, I have 20" 50 series so a narrow side wall. Plus once you drive down the highway you'll get psi raised 2-3 due to heating up of tires. So I always put air in or out before driving it, when it's cool outside like early morning or early evening or at least when car has been in complete shade for a while. That way I get a good baseline temp and pressure that has had no influence on warmer midday temps. Like I mentioned earlier factory recommended 33+1 psi is where I set my tires giving me a slight improvement in rolling resistance.

BTW the manual mentions higher pressure be used when travelling over 160 kph or 100 mph for any length of time. That's because the sidewall flexing that occurs where the tire hits the road causes internal friction on the rubber and plys found in the tire sidewalls. This heats up the tire considerably and will shorten tire life if run at those speeds over a long period of the tires life. So no it's not going to cause a blow out or anything like that, but the tire's health or performance will be reduced slightly. Remember these tires are H (130 mph) or V (149mph) rated so they can handle constant high speeds with no problem.