pearl85

when I test drove it must have been with 17" wheels now I have the lux package with 18" wheels and low profile tires (Dunlop Sport Maxx F 225 40R 18 and R 255 40R 18). The ride is far more stiff and bumpy. Is it the tires? What do you suggest for new ones? All ideas are most welcome. And thanks.

mcfly

Check your tire pressures to make sure they're not overinflated.

Failing that, I'm sure there are lots of people on this board with the 17's that would be willing to trade with you.

If it's still to firm after that, you bought the wrong car... it may be a Lexus, but it's a SPORTS sedan.

rominl

iTrader: (4)

i'd say it's mostly the 17s to 18s change

4TehNguyen

iTrader: (1)

yup lower profile tires will do that, i woudlnt get new tires now, just wear those out and check up on tire rack reviews for better ones. OE tires always suck anyways

gsrthomas

iTrader: (1)

I think the ride quality with the 18inch wheels is fine.

The IS looks 100% times better with 18inch wheels then the 17inch ones. There is way to much wheel gap with the 17's.

mcfly

Dunlop Sport Maxx's aren't all that bad of a tire. Any replacement isn't going to offer an improvement in ride quality assuming you keep the same profile. A switch to 17's with a wider sidewall tire is probably your best bet. Like I said, there are probably a ton of people here with 17's that would want to trade for your 18's.

4TehNguyen

iTrader: (1)

yea for ride quality you cant really go anywhere with 18s, but from a performance standpoint there are much better ones than OE

dfw350

for performance youre better off with a bigger rim?
only thing you can be better off with a bigger rim is traction.
everything else is really hindered, think physics its a lot harder to get a bigger wheel spinning fast than a small wheel.

4TehNguyen

iTrader: (1)

i was comparing the OE 18" tires vs what else you can get 18" tires. With a 350s torque I dont think wheel weight is that much of an issue, when you put heavy wheels on a 4 banger thats when you really start noticing it.

Lem144

I tested cars with 17s and 18s. The 18s were way to rough on Boston's roads. You feel all the joints in the road. Yes it's a sports sedan but I can live with the 17s. Plus then I don't need snow tires. The 17s also last 5k more miles than the 18s.

tqlla3k

iTrader: (1)

You can increase your front tire diameter by 1" by moving up to 235/40/18s

Dont know if it will mess up the speedo though, or if it will rub

4TehNguyen

iTrader: (1)

it will mess up speedo, speedo has a relationship to the overal diameter of the tire/wheel combo

I use 215/35/18 on my current car (not a lex) with lowered suspension, I drove the 18" IS350 at the taste of lexus thing and it felt a lot smoother. I guess im used to rough suspensions like some

tqlla3k

iTrader: (1)

Are you certain that the Speedo is calculated off the front wheels? Or are you assuming they are

vp911

It is probably the summer tires and the increase in size. I would probably try to trade in the tires at a local tire place for the michelin pilot sport a/s. They will probably be quieter, smoother, and last longer.

4TehNguyen

iTrader: (1)

im assuming, it would be the most logical, and its closer to the gauge cluster than the rear