tqlla3k

iTrader: (1)

I dont like the thin profile of the front tires, so I want to get tires with bigger sidewalls. And I want more steering response. Hopefully wider tires will help there.

I really want to get 8.5" wheels for the front with 245/40/18s(24"Outer Diameter), so it will be closer to the 25"OD of the rears.

I could go with 235/40/18(23"OD) on 8" wheels, but I would definately rather the 245/40's. I would be using the G-Spiders BTW.... one day

Anyone with wider 18s or 19s or 20s able to fit tires on without rubbing?

shaolin

iTrader: (2)

wait for the hyper rev magazine to come out. I'm sure then you will have a lot of choices.

I wanted to get wide rime and tires for the front too so i'm waiting for that as well.

Tony1

The reason most cars come with narrower tires in the front as opposed to the rear, is
that, the wider you go in the front, the less steering repsonse you get.. ie: I used to have a 94 300zx tt, with 225's in the front, i decided to be a genius and change them to 245's. and wowwww what a difference in steering repsonse, it almost went numb.. I'm not sure this is the case with our IS's, but in all likelyhood it is...

tqlla3k

iTrader: (1)

When I switched up to 245s on my 3000, I liked it. Basically, I want the steering to be a little more stiff.

When you changed the tire in the front of your 300? If you had less than 8.5" Width on the 300s front, with 245s, I can see why the car would feel less responsive.

Tony1

You have a point, the front rim width remained stock which was about a 7.5 or 8"..
But doesn't where the rubber contacts with the pavement make the most difference?
Eh who knows, just watch out because once you buy new rims and tires, then
drive the car around with them, tthe store will usually will not take them back!..

newr

If you want more steering response, wider front tires and bigger sidewalls will not get you there.

tqlla3k

iTrader: (1)

The Larger sidewalls will hurt the cornering. But I do not like the way 225/40/18s look on the tire. Also I dont think they offer adequate protection to the wheels. 245/40/18s have larger sidewalls but they are still thin enough to feel stiff.

Maybe I am explaining myself incorrectly, the car currently feels disconnected from the road, IE, its too easy to turn the steering wheel left and right. I want the steering to feel more firm. -- I want the steering wheel to feel more weighted, I guess.

SilverBolt

As you increase the sidewall height you decrease steering response. Can't have it both ways.

shaolin

iTrader: (2)

my stock s2k front is 205 and now i have 255. The extra grip in the front just

tqlla3k

iTrader: (1)

Are you so certain of this? I know it will decrease handling. but I dont think it will have a huge affect on the steering, esp if the PSI is kept at recommended levels. 245/40/18s are larger than the stock 225s, but they still have pretty thin sidewalls.

Well anyway, I am more worried about getting the wider tires to fit in my wheel well.

SilverBolt

If you are talking just a profile/sidewall change then yes. It's just physics. Increasing the width will also affect the outcome. Are you looking for grip, turn in, or both? If it's just cosmetic don't worry about it. Unless you are making a very radical change, on the street you probably won't notice a difference. Other than it will ride smoother and quieter.

tqlla3k

iTrader: (1)

Well, I am not looking for increased handling. I want the steering wheel to feel tighter/heavier. Its too easy to turn the wheel IMO.

4TehNguyen

iTrader: (1)

^^^I guess wider tires will do that for you, on my current car (not a lexus), i went from 205/50/16 to 215/35/18 and the steering wheel was a lot stiffer, felt great. The stock OEM tires were crappy for any type of driving and the new 18s were a lot stickier, so im sure that was a factor also

SilverBolt

It's possible a wider tire might help. The light feel is from an over boosted power assist. What we need is a way to reduce the amount of assist in the power steering. I believe the steering on the IS is electronic so I am not sure how or if that can be done. If it is mechanical then a pulley change on the power steering pump can help depending on the system.

rljones

I too have the 18" rims on my IS350 and would like a higher profile tire. The stocks are 225/40/18 F and 255/40/18 R. These calculate to a height of 90 mm sidewall for the Fronts and 102 mm Rears (circumference is 25.1" F; 26.0" R).

Sizes in 18" that are wider are limited (I've been looking primarily at summer performance).

For front examples, a 235/40/18 only increases the sidewall by 2 mm; hardly worth the effort. Better increases would be 225/45/18 same width but sidewall now at 101 mm (almost 1/2 an inch taller sidewall, meaning the whole car will also ride this much taller) and a circumference now of 26 like the std rear.

A front of 235/45/18 is about half an inch wider and has a side wall of 106 mm (or just over 1/2").

For the rear, the only wider size I've found that might work is a 255/45/18 (13 mm taller with a circumference of 27") and a 285/40/18 (12 mm taller with a circumference of 27").

Some of the brands I've found in these sizes are: Pirelli Rosso (225/45/18 and 285/40/18); the Nero M+S is only available in 235/40/18 (not signficantly larger) and a 285/40/18. The Nero does come in a 245/45/18 but the dimensions may not fit (it has a sidewall increase of 20 mm or 3/4" and the circuference is 26.7").

Pilot Sport PS2 is in 245/40/18 (8 mm taller with a circ of 25.7") and 275/40/18 (8 mm taller with a circ of 26.7") are a passably larger choice.

Goodyear Eagle F1 GS-D3 are in more sizes that could work: 245/40/18, 235/5018 and 245/45/18 for the fronts and 255/45/18 and 275/40/18 for the rears.

This is not an exhaustive search but may be helpful to some.