RX450 19" wheels

hcimc · June 11, 2016

I have recently upgraded from a 2007 RX400H to a 2011 RX450H and am disapointed with a reduction of smoothness of ride. The "new" one seems more unsettled on country roads and has more noticeable road noise. The previous model was also less tiring over long distances (mind you, now being 83 may have something to do with it!). I notice that being somwhat harsher has been mentioned in previous topics. I put this down to the change in standard wheel size from 18" to 19" and that the previous driver's seat had 90,000 miles of wear.

Has anyone tried fitting 18" wheels to an RX 450 and does it make an improving difference to comfort. I no longer mind a bit of roll on corners.

Any (polite) comments will be much appreciated.

rayaans · June 12, 2016

18s do make a difference yes.

Check your tyre pressures too. I run 37psi but Lexus recommend 32 on the RX so you probably want to put it at 32psi all around

Road noise will be down to the tyre choice itself. The 3rd gen RX is quieter so it's the only thing it could be.

hcimc · June 12, 2016

Thanks for the reply. Can I ask if you have actually tried 18" wheels or if, like me, your expectation is that this would be the case?

I take your point about pressures and the choice of tyre being the main factor in noise generation.

rayaans · June 12, 2016

3 hours ago, hcimc said:

Thanks for the reply. Can I ask if you have actually tried 18" wheels or if, like me, your expectation is that this would be the case?

I take your point about pressures and the choice of tyre being the main factor in noise generation.

I drove an SE a while back. It was a 2012 loaner vehicle and it came from the factory with 18" wheels.

It was smoother and TBH there was no difference in wallowing as thats to do with the suspension.

DanD · June 13, 2016

Personally, I do not think that you will see a lot of difference changing down from 19" to 18". I have owned a 400h previously and I always thought the 450h was quieter. However, I would suggest that, as the car is quieter and offers better insulation from the outside than the 400h, the noise generated by the tyres may appear louder.

Noise and comfort will be influence by tyre choice, tyre wear... and yes, seat wear too! Like Rayaan I'd recommend that you check your tyre pressure and also how much life they have in them. Swapping to new and different tyres may be the solution.

If you bought the car from a Lexus dealer, I guess you could also ask to drive another one of their cars for comparison.

hcimc · June 13, 2016

Thanks Dan. I am beginning to wish I hadn't mentioned noise as it is the more usettled ride over Cotswold roads and lanes that concerns me most.

When I mentioned 18" wheels to my dealer, the expression on his face said he hadn't been asked that question before i.e. it would be a most unusual fitting.In the unlikely event that someone has actually tried it, I would be pleased to hear about it.

robski · June 14, 2016

If you do decide to change your wheel size remember that your insurance company will see this as a modification and will happily lighten your wallet accordingly! If you have a particularly unhelpful insurer then they could even cancel your policy!

In my humble opinion tyre choice is a much better option to play with. Tyre pressures can be easily played with at home and hopefully it shouldn't take you too long to find the sweet spot you're looking for!

Out of interest, what tyres do you have fitted at the moment and do you recall what tyres you had fitted to your previous car?

fogey · June 19, 2016

I remember someone commenting on his first drive in the Rx450h that Lexus had ... "ruined the ride" ... so that he could feel ... "every ridge and bump in the road" ...(presumably compared with his Rx400h). Certainly the reviews on the Rx 450h frequently complain about the unsettled ride, whereas on the 400h these criticisms are notably absent. One reviewer commented that the top model 450h with 19 inch wheels and air suspension gave a worse ride than the base model with standard suspension and 18 inch wheels. I guess you could look for a base model with 18 inch wheels and then ask to drive it, to see how it felt to you, before committing yourself to smaller wheels.

I also remember someone experimenting with tyres pressures too, saying that the optimum ride was very dependent on this. So I guess that was also someone else who was in the same position as you are now. Certainly experimenting with tyre pressures is the easiest thing to try first. With the 2011 model I think you will still have the traditional tyre valves too, so you will not have to play around with that pesky Tyre Pressure Monitoring System which would complain if it thought the tyre pressures were too low.

So what you are saying is in line with everything I have read so far and it always seems that 18 inch wheels are indeed the way to go for maximum ride comfort.

It seems to me that there is no advantage at all fitting larger wheels to the Rx, except perhaps from the perceived cosmetic angle. The Rx is aimed at people who prefer a smooth, quiet ride and an effortless driving experience. Cars fitted with larger wheels and low profile tyres are more suited to drivers who wish to spend a lot of effort driving along twisty country roads to see how fast they can go before they end up in the ditch.

Such ludicrous driving is more suited to the younger generations and like you, I definitely do not belong there. So you think very much as I do and support my inclination to remain with my older Rx400h rather than "upgrade" to the Rx450h.

Please let me know if you do find a way to make your Rx450h ride as well as your last Rx400h as I might follow you there some day, although I do have other reservations about the Rx450h which I would also need to address.

hcimc · June 20, 2016

Robski and fogey,

Many thanks for your comments.

robski - The tyres fitted are Dunlop SP Sports, 235 55 R19 101V, which have a quietnes figure of 69 db, lower than most. Pressure was measured at 36psi all round. Now, I'm something of a fogey myself, well into my eighties, so experimenting with pressures may be a possibility but not an attractive idea!! My days of "get out and get under" are long gone!

Since my original enquiry I have now checked what the standard pressures should be. The hanbook and the lable on the driver's door-jamb, both say 36psi for 18 inch wheels! Yet the car was supplied with 19" wheels! When the car was being demonstrated, I asked about wheel size and the salesman said 19" straight away.This raises the question of what a loss adjuster might make of all this in the event of a claim. I have emailed my supplier (Lexus Cheltenham) about this and am awaiting their reply.

I will ask about a base model, what size wheels it has and if they have one available to drive. However, dealers don't usually have base models as their demonstrators but thank you for the suggestion.

So- for the timebeing- an ongoing saga.

rayaans · June 20, 2016

17 minutes ago, hcimc said:

Robski and fogey,

Many thanks for your comments.

robski - The tyres fitted are Dunlop SP Sports, 235 55 R19 101V, which have a quietnes figure of 69 db, lower than most. Pressure was measured at 36psi all round. Now, I'm something of a fogey myself, well into my eighties, so experimenting with pressures may be a possibility but not an attractive idea!! My days of "get out and get under" are long gone!

Since my original enquiry I have now checked what the standard pressures should be. The hanbook and the lable on the driver's door-jamb, both say 36psi for 18 inch wheels! Yet the car was supplied with 19" wheels! When the car was being demonstrated, I asked about wheel size and the salesman said 19" straight away.This raises the question of what a loss adjuster might make of all this in the event of a claim. I have emailed my supplier (Lexus Cheltenham) about this and am awaiting their reply.

I will ask about a base model, what size wheels it has and if they have one available to drive. However, dealers don't usually have base models as their demonstrators but thank you for the suggestion.

So- for the timebeing- an ongoing saga.

The Dunlops are NOT rated at 69db. They're rated at 71db. They were standard fit on my RX and I changed them when they wore out to Michelin Latitude Tour HP and they're eerily quiet.

36psi is too high, the RX is rated at 32psi I believe. Although I prefer 37psi as it feels more solid rather than cushy.

DanD · June 20, 2016

1 hour ago, rayaans said:

The Dunlops are NOT rated at 69db. They're rated at 71db. They were standard fit on my RX and I changed them when they wore out to Michelin Latitude Tour HP and they're eerily quiet.

36psi is too high, the RX is rated at 32psi I believe. Although I prefer 37psi as it feels more solid rather than cushy.

Spot on.

I too switched to the Michelin Latitude and I love them. Performance is very good, and they are very quiet. You will find that you aim for the recommended 32psi, it will make a difference to the ride.

fogey · June 20, 2016

21 hours ago, fogey said:

I remember someone commenting on his first drive in the Rx450h that Lexus had ... "ruined the ride" ... so that he could feel ... "every ridge and bump in the road" ...(presumably compared with his Rx400h). Certainly the reviews on the Rx 450h frequently complain about the unsettled ride, whereas on the 400h these criticisms are notably absent. One reviewer commented that the top model 450h with 19 inch wheels and air suspension gave a worse ride than the base model with standard suspension and 18 inch wheels. I guess you could look for a base model with 18 inch wheels and then ask to drive it, to see how it felt to you, before committing yourself to smaller wheels.

I also remember someone experimenting with tyres pressures too, saying that the optimum ride was very dependent on this. So I guess that was also someone else who was in the same position as you are now. Certainly experimenting with tyre pressures is the easiest thing to try first. With the 2011 model I think you will still have the traditional tyre valves too, so you will not have to play around with that pesky Tyre Pressure Monitoring System which would complain if it thought the tyre pressures were too low.

So what you are saying is in line with everything I have read so far and it always seems that 18 inch wheels are indeed the way to go for maximum ride comfort.

It seems to me that there is no advantage at all fitting larger wheels to the Rx, except perhaps from the perceived cosmetic angle. The Rx is aimed at people who prefer a smooth, quiet ride and an effortless driving experience. Cars fitted with larger wheels and low profile tyres are more suited to drivers who wish to spend a lot of effort driving along twisty country roads to see how fast they can go before they end up in the ditch.

Such ludicrous driving is more suited to the younger generations and like you, I definitely do not belong there. So you think very much as I do and support my inclination to remain with my older Rx400h rather than "upgrade" to the Rx450h.

Please let me know if you do find a way to make your Rx450h ride as well as your last Rx400h as I might follow you there some day, although I do have other reservations about the Rx450h which I would also need to address.

When I collected my Rx400h from the last service I had a very bumpy ride home so I checked the tyres and found them all at 36psi. My handbook states 32psi for normal driving and this is where I usually run them. I can get an even better ride at 30psi but then fuel consumption starts to suffer.

So if your tyres are up at 36psi too then I am sure you might find most of your problems disappear if you drop them to 32psi. It's strange that your car sticker and hand book both give 36psi .... as strange as I found mine there at the last service.

I too was looking for those Michelins when replacing my tyres, but couldn't find any at a competitive price, so I kept with the Dunlop Sports, as I needed new tyres rather quickly for the pending MoT. From the date code it seems my tyres were still the original fit (as at 2008, so 7 years old) and although they were not down to the wear markers they were rather perished with small cracks appearing within the tread. I don't find the tyre noise intrusive at all and it certainly doesn't spoil the very quiet ride I enjoy when driving the car. So as always its a matter pf personal preference.

If you still want to know what 18 inch wheels feel like on the base model, I guess you might need to search for a used one, I think its the SE for your 2011 model year and I think there must a few around, its just a matter of finding one. I am sure Lexus would let you do this, if only for your peace of mind, otherwise try another trader or even a private seller as they are usually very obliging.

rayaans · June 21, 2016

In the 450h handbook, it only says 36psi for the 18" wheel and tyre combo, it says 32 psi for the 19"

fogey · June 21, 2016

4 hours ago, rayaans said:

In the 450h handbook, it only says 36psi for the 18" wheel and tyre combo, it says 32 psi for the 19"

This would explain hcimc's dilemma in trying to understand the label on his car and what is in his handbook. It might also explain why my car came back with 36psi, even though the Rx400h handbook states 32psi for the 18inch wheels, which are standard throughout the whole Rx400h range ...

So potentially an area for much confusion. ...even within Lexus it seems.

So the question now is what is the actual pressure now in his 19inch wheels ? If he has measured 36psi then that will go a long way to explaining his ride difficulties and Lexus have supplied his car with the wrong tyre pressures !

And it seems if he opted to change his wheels to 18inch and then set them to 36psi he would gain little ride improvement, based on my experience with such an arrangement.

So the ride in the 450h is always going to be worse than the 400h, either due to the larger wheels or the 18inch wheels running at 36psi.

It seems that the Rx450h has been set up for a bias towards improved handling rather than optimum ride comfort and this goes a long way to explaining some reviews complaining of an unsettled ride, particularly around town, where the road surface is typically worse and the car always has to be driven slower. Such road imperfections would not be so noticeable at higher speed of course.

Perhaps this is even more so for the F-sport variant as I would guess the car suspension there is even more biassed towards better handling.

ChrisKaye · June 22, 2016

Same happened to me on an RX300 - I took my recently refurbed wheels in to get tyres fitted and it can back at 36psi!

I usually run 34psi all round but handbook states 32psi recommended...

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PCM · June 25, 2016

Think I'll check MY tyre pressures today.

I think I keep them at about 34psi too...

hcimc · June 26, 2016

Many thanks for the last 4 items. Ryanns, - I have now found the correct page (p. 163) in my handbook which states 33psi for 19"tyres; different from your 32psi but then, what's a 1psi difference between friends?!

I have reduced the pressures on mine to 33psi and do not notice any change in the ride. It is still jittery. So, I carry on hoping someone who has changed to 18" tyres to join the discussion and will try my supplier next time I am in the vicinity.

Psk · July 10, 2016

I have a F sport model and tried 29.5 psi on all wheels.This has improved the ride in town and is not as jittery as before with 33psi.I haven't noticed any changes in mpg which is 35.7 in town and 41 in motorway.

rayaans · July 10, 2016

1 hour ago, Psk said:

I have a F sport model and tried 29.5 psi on all wheels.This has improved the ride in town and is not as jittery as before with 33psi.I haven't noticed any changes in mpg which is 35.7 in town and 41 in motorway.

29.5 psi is seriously low. The tyres look nearly flat on 32psi. I run 37psi and I actually find the ride better than on 32psi for the F Sport.

Psk · July 11, 2016

I have Dunlop tyres all round, maybe the ride is too harsh with these tyres on 33 psi.I can feel every bump on the road especially in town.on 29.5 psi the ride gets settled and only the worst bumps cause some noise in the cabin.Rayaans I will try on 37 psi.Have you got Dunlop tyres as well.How is your mpg.

Read in a blog that Michelin tyres are quiet and improves ride quality of Rx.

Hcimc you could try lowering tyre pressure to 29.5 psi and see if it makes the ride comfortable in your Rx.

rayaans · July 12, 2016

17 hours ago, Psk said:

I have Dunlop tyres all round, maybe the ride is too harsh with these tyres on 33 psi.I can feel every bump on the road especially in town.on 29.5 psi the ride gets settled and only the worst bumps cause some noise in the cabin.Rayaans I will try on 37 psi.Have you got Dunlop tyres as well.How is your mpg.

Read in a blog that Michelin tyres are quiet and improves ride quality of Rx.

Hcimc you could try lowering tyre pressure to 29.5 psi and see if it makes the ride comfortable in your Rx.

You mentioned you have an RX F-Sport though? If you were fussed about ride quality surely you should have gone for the other models in the range rather than the stiffest one?

DanD · July 13, 2016

I would say that running on 29.5PSI might indeed make for better comfort, but is it not rather dangerous, causing undue damage to the tyre walls, reducing the effectiveness of the ABS system, and also affecting grip when going around bends and roundabouts?

ColinBarber · July 13, 2016

8 hours ago, DanD said:

I would say that running on 29.5PSI might indeed make for better comfort, but is it not rather dangerous, causing undue damage to the tyre walls, reducing the effectiveness of the ABS system, and also affecting grip when going around bends and roundabouts?

Grip should be ok, if not better, but you will wear the tyres and potentially stress the sidewalls. Another issue with running low pressures is you are likely to damage your rims if you hit a pothole.

Psk · July 14, 2016

When I did the test drive for f sport it felt quite smooth as the road was also nice.However after buying the car and driving in my town it became apparent that the ride is unsettled in town due to terrible road surfaces where I live.So I have to really go slowly in town that helps to smooth the ride and it improves mpg.Today a short run in town gave 46mpg with tyres inflated at 29.5 psi.I am going to increase tyre pressure to 33 psi and reduce speed in town so will be driving more on Battery power.I bought the car due to its looks in f sport guise.Fsport model has lateral dampers in addition to coil springs to help with cornering ability and also has better steering feel and weight than other models.The premier model comes with air suspension and it is also reported to have a harsh ride in town.so basic coil sprung Rx's might have a better ride than high f sport and premier models.