RX350 Wheels, 2015 Vs 2021?

[Gamalot]

My 2015 RX350 had 18 inch wheels and I bought a second set of the original OEM wheels with TPMS sensors and used them with Blizzak winter tires. I traded the 2015 for a new 2021 RX350 that has 20 inch wheels but I still have the 18 inch winter set with lots of tread left. Will the 2015 18 inch wheels fit the 2021? I suspect the bolt pattern remains the same but my concern is have they increased the caliper size for 2021 that would cause a clearance issue?

[mrolds69]

I don't know for sure, but I assume they will physically fit your 2021 RX. I believe the problem is you can't just switch from 18's to 20's w/o speedometer and computer issues. There are sensors that will read differently.

[Gamalot]

8 hours ago, mrolds69 said:

I don't know for sure, but I assume they will physically fit your 2021 RX. I believe the problem is you can't just switch from 18's to 20's w/o speedometer and computer issues. There are sensors that will read differently.

I thought the same with my 2016 4Runner when I swapped to 17 inch wheels and tires for winter from the original 20 inch wheels and tires. It turned out to be fine since the 17 inch tires were the same height and circumference as the stock 20 inch ones so it made no difference. I am not yet ready to swap to winter treads on the new RX but when the time comes I will have to make 2 important inspections. Will the smaller wheels clear the brake calipers and is there a big difference in the actual height/circumference of the tires that could throw off my speedometer calibration. All these wheels have the correct TPMS sensors installed so no issue there.

[Les Lex 2018]

My 2020 RX350 has Michelin Premier LTX 235/55R 20 tires. If you go to TireRack and look it up, it shows that it has a very important spec.

It's called Revolutions per mile = 690.   That is the number your speedometer is expecting to use in order to be accurate.

So look up your older 15 inch tire and do the same thing.  Tre rev/mile should be about the same.  Which you already know that it is.

But it's just a good exercise to do when you are replacing your tires on any vehicle.

 

[Gamalot]

1 hour ago, Les Lex 2018 said:

My 2020 RX350 has Michelin Premier LTX 235/55R 20 tires. If you go to TireRack and look it up, it shows that it has a very important spec.

It's called Revolutions per mile = 690.   That is the number your speedometer is expecting to use in order to be accurate.

So look up your older 15 inch tire and do the same thing.  Tre rev/mile should be about the same.  Which you already know that it is.

But it's just a good exercise to do when you are replacing your tires on any vehicle.

 

Thanks Les, think you have missed my question specs. My older 2015 RX wheels are an original stock 18" set with just winter Blizzak tires. I think but can't be sure some lesser models of the 2021 RX350s come with 18" wheels but the upgrades are either 19 or 20". Our 2021 came with the upgraded Michelin LTX 235/55R20 wheels and tires you have.

If the 18 inch wheels will fit, which is my question, the only other parameter will be if my 18" tires are the same height as the 20" tires we both have. I am not sure but I think the size 235 is the sidewall height and the 55R is the width of the tire. 235 in an 20" wheel and tire could be about the same height and circumference as 265 in an 18".

[RX400h]

The tire diameter calculation requires converting from inches to mm but you can skip that and use this handy calculator:

Tire Diameter Calculator | Calculate Diameter of a Tire (calculatorpro.com)

 

 

[Les Lex 2018]

As far as fitting, you can go to ebay and look for sellers that have fit charts and they show you which OEM wheels will fit on what year model cars.  My guess is that a 2015 OEM 18 inch wheel will show that it will fit on the 21 models.  

 The 18 inch tire you have, had to have close to the same RPM number if Lexus did not change to a different RPM number with the 16 to 21 models. 

Measuring the diameter of the tires horizontally, not vertically as you did is just another way of comparing the RPM.

[Gamalot]

8 hours ago, RX400h said:

The tire diameter calculation requires converting from inches to mm but you can skip that and use this handy calculator:

Tire Diameter Calculator | Calculate Diameter of a Tire (calculatorpro.com)

 

 

I am not sure I did this correctly or what these numbers actually mean. The best I have found is Yes, my 2015 18" wheels will fit on the 2021 RX. 3 different size tires are listed.

235/60R/18 =29.10

235/65R/18 =30.03

235/55R/20 =30.18

I suspect with nearly an inch of difference it could throw my speedometer off a little but when I do swap I should be able to match what the speedo says against what the GPS is reading and adjust my driving speed accordingly. Whether or not this might mess with any of the onboard computer systems is another unknown.

On our 600 mile trip we averaged 25 miles per gallon and I used the Radar Controlled Cruise most of the trip. At first I did not like it much but once I fully understood how it functions it was helpful to a degree. It just felt weird at first when I had the cruise set at 70 MPH but if there was a car in front of us going a little slower it kept us back a safe distance and adjusted our speed until I would pull out to pass.

[RX400h]

When I checked tirerack.com, they list your 2015 RX350 OEM tire size as 235/60/18 which has a diameter of 29.10 inches

The 2020 RX350 OEM was either 235/65/18 (30 inch diameter) or the 235/55/20 (also 30 inch diameter)

So it looks like you'd have to have the 235/65/18 size tires on your 18-inch wheels in order to retain the same overall diameter as what was available on the 2020 RX350.

[Gamalot]

1 hour ago, RX400h said:

When I checked tirerack.com, they list your 2015 RX350 OEM tire size as 235/60/18 which has a diameter of 29.10 inches

The 2020 RX350 OEM was either 235/65/18 (30 inch diameter) or the 235/55/20 (also 30 inch diameter)

So it looks like you'd have to have the 235/65/18 size tires on your 18-inch wheels in order to retain the same overall diameter as what was available on the 2020 RX350.

Thanks Dave for all your research. My 18" wheels have very nice Blizzak tires but the size is 235/60/18, 29.10.

[RX400h]

You're welcome, Gary. Can you sell the existing tires and purchase the 235/65/18 size tires? 

[Gamalot]

The RX350 is my wife's car and now that she is retired I plan to keep it parked in the garage all winter except on the nicest of days. She will be Grounded when the roads are crappy or she can drive my 4Runner. The Lexus has to last us lots of years. I will probably sell the wheels and tires when winter gets a bit closer here.

[Les Lex 2018]

Reminder her to WATCH THE CURBS...  Your 20 inch wheels ride below your traditional square shaped curbs.

I like the tapered curves but they don't use them here. 

Never park in the end spot and forget it's next to a curb and cut out at an angle - OUCH!!!!

Right lane turns - turn wide at intersections.

I will deny that I speak from experience here...

All them buttons and controls and so much to do while driving ;+)