First post -- thanks in advance for your replies.

New owner of an 06 GS300 with 18-inch wheels upgrade option.

Last owner just replaced the OEM tires with Goodyear Eagle GT 245-40-18.
I can feel every bump in the road. Way too hard for me. (They're all but brand new -- maybe 400 miles on em.)

Thinking of replacing them with some softer, touring tires, like the Kumho Ecsta LX Platinum.

Question is: will I be able to tell the difference? One mechanic told me yes. Another said no, because the sidewalls are so short with this size tire.

What has your experience been?

Thank you!!

 

Good year is usually on the soft side as far as tires is concerned.

 

I'm assuming the Goodyears are not run-flats....

 

No, not run flats.

I'm coming to this GS from an ES300. Softest, quietest car I've ever been in.
This GS is is much firmer, which I expected. But the road noise and feel has been a surprise. On some roads, even at low speeds, it's extremely shaky in the cabin.

Is it the GS, the 18-inch wheels, or the tires?

And would changing the tire decrease the road noise?

Thanks again -- really appreciate your insights.

 

tires can decrease road noise.

but they're probably not going to do much about harsh ride. the suspensions are tuned differently between the es300 and the GS

 

If you are going to make a significant improvement in the ride with tires, you will have to go to something with a higher aspect ratio. Check the specs on your tires with Tire Rack and find a touring tire that matches the diameter of the current tires but in something like a 50 or even 55 ratio. The tread will be much narrower but more cushion in the sidewalls. I would suggest a very quiet tire such as the Michelin Primacy MXV or the Bridgestone Turanza Serenity.

This will be a significant change in the way the car drives. Smoother and quieter with a decrease in turning response and dry braking distance. I made a similar change on my G35 coupe and love the results but it is not for everyone.

Steve

 

Great stuff, Steve, thank you!

So, to be clear: if the current tires are 245 - 40 -18 ...... I'll be looking for a touring tire that's 245 - 50 or 55 - 18 ... yes?

Amateur question, I know. Learning!!

 

if you are going with a higher aspect ratio, you would need to get smaller sized wheels. otherwise your speedometer will be off if you install them on your 18" wheels. so this means you would want 17" wheel, not your stock 18s. your best bet would be to find someone who wants to upgrade their oem 17" wheels/tires with your 18" wheels/tires and do a swap.

 

i wish lexus would put in a tire diameter adjustment feature, where we just enter the number into the computer screen, and it recalibrates the traction control and speedo.

i would love to ride on 18" 50 series

 

it would solve a lot of hassles wouldn't it...

 

i had the same problem with new yokohama yk520 245-40-18 and i returned them and got 245-45-18 michelin primacy mxv4 and the ride is now very smooth. a huge difference.

 

I test drove a GS460 with 18" tires and had a GS350 with 17" tires and there is really not that much difference. A less aggresive thread pattern would make the ride quieter, but since you are in IL, it will have less snow traction. The GS is not an ES, I am sure you know that. No matter what you do, the GS will never ride as smooth as the ES.

 

Thanks for all your feedback. I think the thing to do is "live with it" and get used to it. It's just a different ride. I'm intrigued by bigred08's statement, where you jumped from 40 to a 45 profile on the same car as mine, and it made a difference.

If the difference is 10 or 20% in ride comfort, it's not worth over $1k in new tires to me. If the difference is 50% or more, it may be.

I've driven less than 100 miles on the new GS so far, so I've decided I need to spend some more time.

Thanks again!

 

Its not 50% better trust me. Its hard to put a number on it since the 460 have varible suspension. When its on sport, its stiffer than the 350 on 17", and when its on comfort, it is softer. Since you only have 100 miles on it, I would give it a few thousand more miles and let the suspension lossen up a bit and concentrate on the better handling the GS has over the ES

 

if your upgrading the closest i came up with (figured it quickly, there may be something closer)

245/40/18 - 215/45/18 - 0.39% difference in size

i dont think you will be able to get anything close with a 55 or even 50 series tire. you would have to get a width under 200 to come close.