Lust4Lexus

when you put on your 18 inch rims on, does your car seem slower or less responsive? The reason I ask, is that I am considering to start looking for a set of factory 18's for my LS. The only thing is, I noticed that when I put on factory 17's on my maxima, that originally came with 16's, the car definitely felt more sluggish, as the new rim and tire were heavier. The braking power also went down with the heavier rims. The handling was much better though. Can somebody chime in? I love the feel of my 17's with the MXV4, but the 18's look so much better, that I may get a set of 18's for the non snow months and put some summer rubber on them, and use the 17's for winter. Did the Lexus' that came with the 18's come with a larger set of brakes?

Jabberwock

Braking power will be reduced with larger wheels and tires - assuming larger wheels and tires weigh more and have a larger moment of inertia (more centrifugal force) than smaller lighter wheels.

Should not be a huge difference on only 1 inch bigger wheels but its there. The big problems show up when people put huge oversized size wheels and tires on their pickup trucks and don't have the smarts to upgrade the brakes. The result is severely underpowered brakes and that makes them a danger to themselves and everyone around them.

The need for huge trucks and giant wheels for city driving puzzles me - isn't it easier and cheaper to just get a sign that says "I have a tiny wiener" ?

caddyowner

Generally, moving to a slightly larger diameter wheel with the same overall tire circumference will result in:

- shorter sidewall height
- a firmer ride
- crisper handling in turns.

However, if you have two wheels constructed of the same material, going from a 17" diameter wheel to an 18" diameter wheel adds mass (3.14" x width of wheel) located 1" further from the axle which increases the moment of inertia of the body by an amount somebody with more physics memory than I can calculate. One way to overcome this is to change from a cast to a forged wheel which is lighter and stronger. However, if you've priced good forged wheels, you'll see that prices start at a bit under $1K per wheel and go up from there.

Also, tire construction makes a big difference. More automakers are offering larger wheels and lower profile tires because of the looks and have the tire makers providing tires that don't run as roughly (and don't handle as well) as high performance tires.

I have (heavy) 18" factory chrome wheels for summer and 17" 01 painted silver wheels for winter. I'm thinking of looking for some lightweight 18" painted silver wheels for summer use that won't break the bank.

Lust4Lexus

so by your admission, crisper handling aside, you would say that the factory 18's feel a little heavier on your car. you can feel the difference on acceleration etc?

airtime

I too am currently riding on factory 17's and loving the soft cushioned ride. I long for a set of stock 5 spoke 18's though as it looks great on the car. During summer, I ride on punishing 20's. The 20's performs very well but the ride quality leaves little to be desire. Larger wheels definitely adds weight, metal weighs more than rubber and can add 20+ lbs per corner which is pretty significant in unsprung weight. Luckily, the LS has the large caliper brakes which works well.

caddyowner

I don't think the 18" wheels feel any heavier when I drive, just rougher due to lower aspect ration Goodyear tires. The added weight of the 18" wheel/tire combination may be offset by the softer feel of the 17" wheel / winter tire combination. The 18" tire/wheel combination seemed heavier to lift than the 17" tire/wheel combination. However, I didn't weigh them.

Lust4Lexus

yeah, I love the look of the factory 18's, but don't want to sacrifice power to spin them. I would love to know what the average weight of the factory 17's and factory 18's are and figure out how much heavier a wheel and tire would have to be before the driver could feel a difference in acceleration.

Jabberwock

Beside reducing acceleration and increasing braking performance, heavier weight wheels and tires also negatively affect ride and handling. Anything you can do to reduce "unsprung" weight on a car will generally improve both ride and handling as the suspension becomes more effective with less unsprung mass to contend with.

V8_Fan

Sewell's site says the 18" wheels weigh 27.25 lbs each. No spec for the 17" wheels. I'd say it's hard to compare unless someone takes a wheel and throws it on a scale while changing tires. Other than lighter wheels, you can get lighter tires, which will help. Looking at the Michelin primacy MVX4 specs, the 225/55R17 tires are listed at 26 lbs ea while the 245/45R18's are 28 lbs...yes, the tires for the 18" wheels are 2 lbs heavier!?? If you look at the specs, the 245/45's have a 9.6" section while the 225/55's have a 9.2" section. That is, the tires for the 18" wheels, besides having shorter sidewalls, are wider. This should translate into a larger contact patch on the ground (more rubber on the ground=more traction). Say your tire footprint is 6.5" long x 9.2" wide for the 225/55's. Then the 245/45's would give 4.3% more surface area for traction....not a huge advantage, but it's something.

caddyowner

I wonder what difference a set of 20 lb. 18" BBS forged wheels would make. Tirerack lists some 18" wheels down to about 18 lbs.

Stu

I have factory 18s and aftermarket 17s with snow tires. The ride on 17s is a lot better. I do notice slightly crisper steering on the 18s.

I am trying to sell my OEM 18s ( just wish I didn't put new tires on them )

https://www.clublexus.com/forums/whe...conti-dws.html

As soon as they are sold I'll buy some 17s for the summer.

fergo308

I went from the factory 18's to aftermarket 18's not that long ago and the difference has been all positive.
My factory wheels were 18x7.5" +40 and the replacements are 18x9" +21,which would be close to the amount of alloy difference between the 17x7" zenki rims and the 18x7.5" koukis. I swapped over the same tyres.

Handling and steering response were markedly improved. The half second delay between steering input and vehicle response is now gone and the car corners with more precision. This has come from having the correct width wheel for the tyre's width. The sidewalls are no-longer bagged outwards.

As for the 'will the car accelerate more slowly?' and 'will it lose braking force' questions,the answer is no to both. If you're constantly full throttle off of the lights and usually have your stopwatch out,you may notice 0.05 second's difference in acceleration due to the minor increase in unsprung weight. About the same as having a case of beer in the boot.
You won't care about that difference though,as the handling and braking improvements you'll notice from the wider and lower profile 18's will more than compensate.
Yes,I did say it will brake better. Why? Larger contact patch area,and a lower profile. a stiffer tyre that deforms less under stress,and more rubber on the road to grip with.
Yes,the comfort level will be ever so slightly decreased,but what's your priority? riding on a puffy white cloud,totally insulated from the world around you with little control over what goes on around you,or being in a comfy armchair and being able to control how you turn a corner whilst sitting there?

I say get the 18's. I highly doubt you're going to regret it in any way.


Justin...

5spd97

Putting a larger diameter tire effectively changes your final drive ratio similar to changing to a numerically lower ratio. Think about trying to accelerate a large diameter wheel like a bicycle wheel by gripping and twisting the axle, now think how much easier it would be if tire was 4" in diameter. You could do huge burnouts with 6" tires.

fergo308

It would,if you were actually doing that on the car going from the 17's to the 18's. The overall diameter remains the same as the tyre profile is lowered on the larger wheel. the difference is about 2mm in diameter between a 225/55/R17 and a 245/45/R18. Basically nothing.


Justin...

5spd97

I kind of assumed that people could figure out that i meant rolling diameter hince the analogy to the bicycle wheel. Guess I was wrong.