tthursto

The RX350 that I test drove was fully loaded and had the P235/55R18 tires and I was relatively impressed with its handling compared to other SUVs I was considering at the time. However, to save a bit of money I ordered my car with only the P225/65R17 Michelin Energy LX4 tires thinking the handling would be comparable. Boy was I wrong and naturally it was too late by then to change my mind! It is my understanding that there is no other difference such as spring rates etc. between the two wheel options. If that is correct, I am seriously considering putting snow tires on my 17 inch rims this winter and buying new 18 inch rims with performance all season tires to match next spring. Hopefully that will give my RX350 the handling I experienced on my test drives. Any comments please?

The G Man

Going from 17 to 18 should not make that much difference. Did both RX have the same tire, did the 18" one have performance package?

RXSF

...probably had the performance package...

the 18" only serves to look better and to wear out faster

mandyfig

I was visiting Chicago last week, Schaumburg area to be exact and found a bunch of RX330-RX350 running around (not as much as ATL has) but see that the 7 Spoke standard 17" wheel is predominant. Only 1 out of 10 RX's I saw had the 5 spoke 18" premium. I did see 1 with the 18" Sports 5 Spoke. Interesting.

Lexmex

Depending on the weight of the tires and rims involved, there is going to be some unsprung (rotational) weight differences that will effect MPG and acceleration, but likely not enough to notice by the seat of the pants.

Seadee456

Up north, most AWD RX's come with the 17" wheels. Down south, they all come with 18" wheels no matter the drive. I guess they figure we like more bling.

tthursto

To the best of my knowledge, there is no such thing as a performance package in Canada. The only performance option available is "18-in Alloys" which is described in the brochure as simply "18-in aluminum alloy wheels with P235/55R18 all-season tires". I'm not sure what rubber was on the demo I drove. However, wouldn't a lower aspect ratio on a non-energy type tire mounted on a larger rim just naturally result in firmer/crisper handling?

Losiho

My RX has 17s. I drove an RX350 service loan car about a month ago with 18s. The steering response is a little sharper with the 18s due to less sidewall flex (the steering is also a little heavier).

But ride comfort is definitely better with the 17s - pot holes are best avoided with the 18s.

MC Wong

My RX came with 17s when I bought the car but I put on some 18s with Bridestone Potenza tyres. I found the handling to be better and more responsive. In terms of comfort I believe that the 17s were not as comfortable but I might just be biased.

Ron_Texas

I did not realize that the 7 spoke was 17", when I bought mine back in June I saw the 7 spoke (from a distance) and did not like it as much as the 5 spoke so that is what I bought, I never looked at the size. With that said, I am not disappointed with the 5 spoke 18" wheels in comfort or handling.

I do like the wheels on the 400h better and had a chance to get a set but decided against it not knowing if they would work on mine with the 400h being electrical and all that technical stuff.

oldcajun

If the tires are the same brand and model (ie MXV4) changing from the 225-60X17" to the 235-55X18 will have the following effects:

1.) The ride will get worse for 2 reasons, the less absorbent sidewalls of the lower profile tires and the additional weight increases the unsprung weight.

2.) Steering will be "crisper" since the lower sidewalls don' deflect as much.

3.) Dry braking and handling will be slightly better

4.) Wet braking and snow traction will be slightly worse with the wider tires.

5.) Fuel mileage and acceleration will be slightly poorer with the heavier tire

With a change this small, the effects will be small. You could likely get as much effect by changing the brand or type of tire.

I wish my RX400h had come with the 17" wheels, but I have yet to see any recent RX here in Arizona without the 18" wheel option.
Steve

jfelbab

My experience with the 17" Michelins on a loaner was that the car was very bouncy. I didn't like the ride at all. I have 18" wheels and Bridgestone Dueler Alenzas on my car and the handling and ride are much superior.

AM1

iTrader: (6)

i almost never see RX's here with 17's.

The G Man

Tires make a big difference, more difference than 17 vs 18"

DaveWray

That is a GREAT answer, the tires make all the difference, yes.