drpepper

I'm about to order some tires for my 3GS 18"

I saw where another poster with the same rims said they got 245/45/18 instead of the 245/40/18. They said it gives a "softer" ride and lessens the wheel gap a little bit (better appearance).

Is this an inadvisable size switch? - I assume the recommended size is recommended for a reason. If it's okay to do, would switching a 245/45 in for a 245/40 provide an appreciable ride difference? Would there be a ride/handling downside for the typical/"non-extreme" driver? What about the speedometer and mileage--would there be any discernible effects there?

Thanks

Kaydee

Better appearance WITH A DROP

BS with the softer ride they say with going lower profile. Lower profile will always give you harsher ride.

rominl

iTrader: (4)

higher profile will be more comfortable for sure, but 40 is pretty high profile already for sport sedan, i wouldn't go for 45. with 45, your car will be higher, looks funny imho

speedo will be off as well, you are going faster than what speedo tells you by a few %

Mesca

iTrader: (28)

And you would lose a small bit of MPG too right?

Kaydee

My educated guess would be that you would gain fuel efficiency because there is less unsprung weight

drpepper

Thanks for the comments, guys. I'm not unhappy with the stock look of my car - Maybe if it were AWD, I might be inclined to try to do something. What I am - is in love with the ride and that has had me absolutely anguishing over potentially negatively affecting it as I have to replace the summer tires that are on the car. If I could actually make an improvement, that'd be gravy.

The net rise in the height of the car would be just over a third of an inch on 45s - that doesn't concern me.

What would concern me would be creating some significant issue out of going to a non-recommended size. The circumference difference would be a factor of .964, so there would be a 1 mph difference per 30 mph between the intended speed and the reading with the larger tires. That doesn't seem significant. It wouldn't surprise me if the tolerance were already at least that loose.

As far as the difference in appearance goes, I found the post I was talking about, The member was Rexus300

45's on his AWD



40's on my RWD



It's kind of hard to tell from pictures, but there doesn't seem to be a glaring difference in apparent size between a 98mm side and a 110mm side.

Now that I found the posts again, maybe I should just PM Rexus300 and see if he's willing to say how the tires are doing.

Thanks again

passnu2

iTrader: (33)

^ I would go with the larger tire. Your ODO will be right on since every lexus I have owned is always off slower then what is says!! Yes it will give a better ride then what you have now. If you dont mind the look the I personally say it will give you what you are looking for!

stvincent

iTrader: (5)

i always thought 40's were little too low profile for 18" rims, even my g35 with 19" stock wheels had 40's. i'm sure it will help w/ the ride quality a bit, but i would get 45's mostly for wheel protection.