I currently run 225 / 55 / 17 summer tires and the same 225 / 55 / 17 size in the winter. I need new summer tires and I was wondering about changing to a narrower width and taller sidewall for the summer .... say a 215 / 65 / 17 ( or whatever size needed to keep the speedometer accurate ) I know it's common to do this " downsizing" for snow tires, but is there any reason not to do this in the summer ? I plan to get a touring tire as I am not interested in performance,I want a comfortable ride.

Also, what is the tallest 17 inch tire I can fit on the LS ? I may even accept a speedometer error.

 

talk to Tire Rack or check their site. Select the tire manufacturer you want to go with, type in the car you drive and compare the various sizes that are offered. They also list the tire circumfrance

 

Especially in a summer tire, when there's a possibility of rain, I would want more width on the ground. The difference may be minimal, but I would think the taller tire would be disproportionate to the car, and you'll have less travel up and down in the wells.

 

Here is a link to a very handy "tire size calculator" that I have used....

http://www.anycalculator.com/tiresize.htm

The caution is to ensure what ever tire you select will fit properly (and safely) on your rims.

Very few people look to go narrower than the OEM tire; the LS430 already has one of the best rides and not sure there is much experience or reports from anyone that has done what you are asking....

I for one would go the other way to get more tire surface on the road (just my opinion).

 

car manufacturers have engineers who look at the whole car, the weight, steering, ride quality etc.
Going outside the parameters that are deemed to be appropriate could negatively impact the ride quality.
wider tires contribute to more aquaplaning. Having 4wheel drive experience I can tell you a skinnier tires does better in snow.
I believe the 17" rim/tire is a good choice. I don't like cars with go-kart like tires on golden basket wheels, neither huge rims with lowprofiles that look as if you are driving on the rims.
Just browse the photos on the 3rd gen LS in the form.

 

The 17" tire is probably the best suited tire for the LS430 for comfort, quietness, and predictable handling. Going to 18 loses some ride comfort and the noise will increase. If possible.... go for the 17s... best suited for our cars.... in my humble opinion. (I'm the owner of a 2001 LS430 with 17s for 9 years)...

 

Agreed. My 2001 has the 225/55/17s and the 2005 runs the 245/45/18s. The 2001 has a slightly better ride, even with 4X the miles. The 18s do fill up the wheel well a little better...

 

I think that what OP wants might make sense under extreme winter conditions, but I wouldn't advise it for normal conditions. On my car it has the 245/45-18's from the factory, and in the winter, I go minus one to 225/55-17 with the snows. imho for a car this size, 225's are already skinny.....if this were a German car it would likely be shod with 275's in the rear and 245's in the front....skinnier than 225 would be detrimental to the cornering, which is already marginal at .73g....

edit just thought of this....remember the original 3rd gen LS' had 16's? How about if you go to a 225/60-16? Now you have gained an inch of sidewall, yet have preserved the 225 stance/contact patch.

 

The pre-2004 LS430s came with 3 tire packages, with 16" tires being the default package, so rest assured that the car was designed for 16".

From the Owner's Manual:
Type A: P225/60/R16 97H, front and rear 30 psi, wheel size 16x7.0 JJ, wheel nut torque 76 ft*lbf
Type B: P225/55/R17 95H, front and rear 32 psi, wheel size 17x7.5 JJ, wheel nut torque 76 ft*lbf
Type C: 225/55/R17 97W, front and rear 35 psi, wheel size 17x7.5 JJ, wheel nut torque 76 ft*lbf

OEM Tires:
Standard: Summer Bridgestone Turanza ER33 P225/60HR16 (Code: 035629) or Summer Dunlop SP Sport 270 P225/60R16 97H (Code: 0391-55) or All-Season Dunlop SP Sport 5000 P225/60R16 97H (Code: 0376-55). Full-size spare with alloy wheel.

Optional: Summer Bridgestone H-Rated P225/55R17 (Code: 096148) or Summer Dunlop SP Sport 270 P225/55R17 95H (Code: 0391-01). Full-size spare with alloy wheel.

Euro-tuned Sport Suspension: Summer Dunlop SP Sport 270 P225/55WR17 97W (Code: 0392-01). Full-size spare with alloy wheel.

17 in. tires are expected to experience greater wear than
conventional tires. Tire life may be substantially less than 20,000 miles,
depending on driving conditions.