Fatter tires on stock 18in rims, yes 255/55/18 !
 

I just wanna let everyone who's interested that I (finally) made the switch to fatter tires. It wasn't easy figuring out what the largest tire one can put on an RX330/350. After a few garage trips, trial and error, research, and some luck, here is the setup that finally works:

HARDWARE:
Wheels: stock 18x7in Lexus RX330 wheels
Tires: Sumitomo HTR4 Sport H/P 255/55/18 M+S, treadwear 480, 10.0in section width, 29.2in diameter
Tires cost: (Tirerack.com) 4x98$ US + 103$ US shipping + 155$ US customs//brokerage (still saved about 200$Cnd had I bought them in Montreal, Canada).
Wheel spacer: 5mm thick (5 x 114.3mm) (5 x 4.5in)
Wheel spacers cost: 4x12$ Cnd
Installation cost: 60$Cnd (cost of mounting 4 tires. No installation for the spacer. it just sits on the disk plate)

SPECS:
Tire diameter: increased by 22mm (0.9in)
Ride height: increased by 11mm
Speedometer error: +2.9% at 100km/h (62mph); reading at 100 km/hr, true speed 103 km/hr
Tire section width: increased by 18mm
Tires/wheels are now about half an inch from within the outer wheel well extremity, compared to about 1.2 in.

SUBJECTIVE RATINGS:
Ride comfort: decreased by 20% from the Michelin Energy MXV4 S8 due to stiffer (reinforced) sidewall of the tire. Comparable to riding the RX on "Low" suspension setting (Air Suspension)
Noise: just a pinch louder than the Michelins, if at all.
Dry cornering grip: increased substantially. Tires don't squeal during aggressive city driving tests.
Handling: noticeably increased. Fatter tires and increase in track (due to the spacers) improve the handling dynamics of the RX. Handling went from "marshmallowy" to "somewhat crisp".
Wet/Snow traction: TBD. The Sumitomos have a tread depth of 14/32 which is one of the deepest you'll find on the market for car/light truck tires for excellent potential wet/snow traction.
Look: The extra 22mm in tire diameter increase gives a more complete filled-in wheel-well look. It actually looks a little dropped. From the rear/front, the extra near 18mm in width plus the extra 5mm spacer width gives the RX a much needed meaner, well planted look, close to what an X5 or Cayenne look like. These latter SUVs have 255/55/18s.

CONCLUSION:
I love the wider-tire look and I'm glad I finally got them safely installed and operational. I would have probably preferred a soter riding tire comparable to the Michelins like the Bridgestone Dueler Alenzas, but at 250$US more a set, the Sumitomos were a no-brainer.

Remember. To avoid any rubbing of the front tires in the inner wheel well while performing a complete steering wheel turn, you must install 5mm wheel spacers at a minimum in the front. For the amount they cost, you might as well add them to the rear to give the car a more balanced look and driving feel. The stock lug/studs are long enough to safely compensate for the 5mm loss in protrusion. Any spacer thicker than 5mm should be installed with additional lugs/studs (costly$$).

Go for it! You now can buy those 255 sized tires for your stock rims! :)

Wider tires will not give the same grip in snow as regular tires, but if you live in Canada, you are familiar with the principal that governs the design of the snowshoe.

I bought an Audi Turbo (used) once and it hydroplaned like crazy anytime it rained, and I could not figure it out, because I had owned a lot of Audis before. The tire expert at a tire shop explained that the previous owner put tires on the car that were too wide for the weight of the car, and that caused the hydroplaning. I put on the factory spec size and the hydroplaning went away, but, of course, it did not corner on dry pavement nearly as well as before.

Every gain you make with a tire factor has a trade-off somewhere. Hopefully the 4 wheel drive will compensate in the snow for the wider tires, but be careful on wet pavement, because once a car begins to skid, they are all the same. (That tip from my experiences as a former Jeep Wrangler owner.)

Very cool. Thanks for sharing.

Thanks for the tip and I agree with your statement. The larger the contact patch, the lower the coefficient of friction on compacted snow/ice. However, I do expect the tires to be far better than the Michelins, which were dangerous to say the least; for two reasons: 1. the Sumitomos tread design has larger blocks. with larger groves in between. The Michelins have smaller, less aggressive blocks with a smoother "straighter" overall tread design (hence the slightly quieter ride). 2. the Sumitomos have 14/32nd of tread depth for some serious snow grip; 5/32nd more than the Michelins new.

In a few months, I'll post a followup on the tires' winter performance.

can you post some pics...im interested to see the wider stance. I've ordered 20" prussian blue Juno Lux wheels but I havent decided on the tires yet. One of the things I was complaining about is the stance. I felt the stock tires were too narrow. I love how the cayenne turbo, X5 and other suv's have the aggressive option at least. I still wish they would come out with an RX450 (or some v8 version) to compete with the other comparable-sized SUV's.

This picture is standard 18'" tires on 1/2 inch wider wheels but different back spacing. They sit about 1 inch wider per side (2 inch total width) but do not change the speedo reading or the ride.

http://i5.photobucket.com/albums/y17...Lexus05002.jpg

http://i5.photobucket.com/albums/y17...Lexus05001.jpg

Aloha,
Larry

cool
 

thats the same specs I just ordered right down to the spacers. thanks for the heads up.

Pics with before 235/55/18 and after 255/55/18 tires
 

We can expect larger OEM tires/wheels in the next gen RX. Till now, we have to take matters into our own hands! ;) Here you go. Enjoy the slideshow:

http://ca.pg.photos.yahoo.com/ph/cor....beg=0&.src=ph

Great! Enjoy the new look/performance.

Cheers :)

thanks for posting the pics...they definitely fill the wheel well pretty nicely...i was just reading a thread on a different forum about filling the tires with nitrogen for a smoother ride, tire longevity, and potential improved fuel efficiency...i wasn't aware that costco fills tires with nitrogen...interesting idea

sweet
 

got the 17s and the razor blades on it now, 18s look "right".
cheers

Tires For RX330:
 

I decided to do something very different for my Lexus RX330...

I changed the tire and rims size completely... I went from the 18" that were on the car to 20" rims and tires. Specifically, I put on Greed Drama's 20x8.5" chrome and replace the 18" Michelans with Hankook Ventus ST RH06 275/40R20's High Performance tires. Looks great!

The 20" rims look cool. I hesitated going that route because of the harsher ride. How do you find the ride?

corradoMR2
Question on the spacers..

where did you get them.. ?

I found some 5mm spacers http://www.evasivemotorsports.com/me..._Code=TO-50705
that come with replacement studs..

Edit..
This says the 255/55/18 will fit but does not mention spacers..
http://www.bigwheels.net

Edit 2
More Spacers
http://www.ezaccessory.com/4_5_Lug_5...acer_p/606.htm
thx
tk

I just put 255/55/18 Bridgestone Dueller Alenza on mine last week..

Did not use spacers..
From what I could tell, I don't have any rubbing.. Rubbing was
reported to happen when the wheel was turned all the way..
No rubbing that I could hear/see..

The Bridgestones have a bit stiffer ride than the Michelins
(could be the air pressure - 36 lbs)
but also about 300 less.. I got them on sale.. buy 3 get one free..
the local Tires Plus matched the Firestone Store price..

Do you have a picture of your Rx with the new tires? how does it look?
i am planning to change mine soon. Its been snowing thick here in indiana and the michelin is sucks.

I like the original poster like the slightly beefier
look..
The Michelins have a less aggressive tread pattern
over the Alenza's..
I posted the images on my web server.. let me
know if you can't see them...

old
http://kewlcat.com/old.jpg
new
http://kewlcat.com/new.jpg

Forgot the side view..
Sideview
http://kewlcat.com/newside.jpg

:thumbup: Nice.....
i like it.....thanks for the pic.....

will changing the tires at a local shop void the factory warranty?

No, not that I am aware of.. unless you are having problems with
the "factory tires" and that would probably have to be a
manufacturer's defect..

hth
tk

anyone know if there are more agressive performance tires avaibale besides the sumitomos? i need to change tires soon. and think its possible to go up to 265?

I use this link for checking tire sizes
http://bigwheels.net/

Use the stock 30 PSI front and rear! Your too high pressure combined with the extremely strong (read stiff) construction of the Alenza H/L will have your car going "boink" over every little rut and bump and really make the dash rattle.

do you think this tire size change will fit on a car with air suspension with or without the spacers

Kat,

tells about the ride comfort noise etc with the bridgestones
thanks

i just made the switch to 255/55/18 nitto 420S. v-rated. i didnt use spacers didnt seem like there was any rubbing. i wanted to go with Y or W rated tires but im not sure if i could get 30K out of them, b4 the car gets returned when the lease is up.

Sorry.. been busy with life lately.. :)

This Tire is great.. found out the stiff ride issue.. very
simple..
I was "told" that the tires were inflated to 35 psi.. when
I checked the pressure was about 42 psi..
go figure.. :-)

The tires were not hot when I checked the pressure so the running
temp was even higher..
I dropped the pressure to 34 lbs.. big big difference..
In fact, I would say they ride as good as the Michelins.. if not better

The tires have alway been quiet even at the higher pressure..

Note to self check tire pressure "after" you get new tires.. :)

Handling is great, very responsive... and the *deeper* tread depth is better
in the rain. In fact, it is pouring here in the city this morning so I will get to
test them again..

Final note.. I would /will buy these tires (this size) again.
I personally have never like Firestone tires, but
this tire has changed my mind.. I have put about 2500 miles on them with no issues (other than me not checking the tire pressure..:p )

I think you will be fine.. I have not experienced any rubbing..
Tested this by doing turns with the steering wheel all the
way to the "stops"..

tk

20's the way to go!

Pics of the 255-55's please? I have to go with the fatter tires. Will this affect any warranty issue with the dealer?

Has anyone looked at the Toyo Proxes ST? They look good.

go with the advan st's.

I will! Thanks.

I looked at the wheel well last night, the front has a tighter gap between the tire and the strut than the rear. It there will be problems with the 255's, it will be up front. Since there has been no reports of rubbing (even after the wheels are completely turned), we should be good to go for the 255's, as stated by prior posts. This change will increase the diameter of the wheel by 0.9 in. Normal is 28.3 in, 255-55 will bring it up to 29.2 in. But the performance will be better on the average, from the previous posts. Just reciting them one more time, for those who have questions.

there is actually more room in the front then the back. the back is real tight.

That's not what I felt...I stuck my hand in between the tire and the strut tower.....a pic would reveal it...I will take some tonight.

I did the "hand check" too but even though it is close, it has never rubbed..
Caveat here: All of my driving is either city or highway.. don't do the country road thing.. :)

The tires have about 3500 miles on them now.. still no rubbing and they are still wonderfully quiet...

hth
tk

it shouldn't rub.

Ok, I am happy.

Hi, I'm thinking of going with 255/55/18 GoodYear Fortera TripleTread's... Rated #1 in the survey at Tirerack.com (above the Bridgestone Alenza's). http://www.tirerack.com/tires/survey...y.jsp?type=HAS

Doesn't sound like spacers are necessary, but, I'm still worried about the rubbing issue. Just wondering if the rubbing issue will be more apparent over bumps or in deep snow (after accumulation)?

Snow is a concern with the wider contact patch, but this particular tire is rated M&S as well so I think it will be okay... :)

Thanks, any input would be appreciated!