Steering "loose" At High Speeds >100 Mph

[Manolo1]

I like my IS350 steering feel all the way to 100 mph, after that it gives me a weird feeling. The feeling is the same you feel when you have strong side winds but there is no wind.

Has any one felt the same?

Is it my imagination? or it is just the way this steering works at those speeds (to force you to slow down... :whistles: :chairshot:

[bartkat]

I haven't notice anything up to 120-130. Car feels very stable. I haven't stayed at those speeds for long, but have run for a few miles at 110 and not noticed anything unusual.

Running tire pressures at 38 front and 40 rear.

[TOOL IS350]

I was running mine at about 105mph for a few miles and everything felt good, then i nailed and got it up to 125. When i was getting up to 125 i think it was just my nervs but i didnt really want to leave it up the past 110 for to long. But at 100 it feels normal to me..

[Manolo1]

I have already read three posts on the same problem, so I know it is not me....it is the electric steering!!!

[bartkat]

My IS350 was one of the first off the line and I have not had the problem. The only ones you'll hear about are from people who have trouble. I doubt it's a design probem or all the cars would have it. I took a cue from a buddy that runs autocross and am running tire pressures at 38 front and 40 rear. Gotta watch that pressure and check it at least once a month. I almost always find them a couple pounds low. The car tracks really well over almost all road surfaces whith that setup.

[CrunchySkippy]

I took a cue from a buddy that runs autocross and am running tire pressures at 38 front and 40 rear.

Bartkat - Those pressures seem high (although likely great for gas mileage and doing 100+mph). The typical downsides to higher pressure are less traction due to the smaller contact patch, uneven tire wear through the middle of the tire due to "ballooning", and a harsher ride.

Are you noticing any side effects at those levels? Do you have the stock tires? I'm surprised an autocrosser made such a high recomendation, especially for the rear.

[bartkat]

That's only 3 PSI above the mfr recommended pressure. The tires are wearing evenly so far. I almost always ran at least 2 PSI above mfr pressure, especially for highway driving. I have the stock Dunlop 18's.

[CrunchySkippy]

I just re-read my 2007 IS manual, and it actually says if you're running 100 mph to run 42.2 PSI in the front and 45.2 PSI in the rear! (That assumes the load index is rated at 91.)

If the load index is 95 (not sure which tires come stock on the 350), that changes to a whopping 45 PSI front and 48 PSI in the rear.

[Cherokee_Outlaw]

That's only 3 PSI above the mfr recommended pressure. The tires are wearing evenly so far. I almost always ran at least 2 PSI above mfr pressure, especially for highway driving. I have the stock Dunlop 18's.

How many miles do you have on your car now? I have the stock Dunlpops.. and at 17.5k they are running thin.. was sort of "forced " to replace the fronts this week...

[bartkat]

That's only 3 PSI above the mfr recommended pressure. The tires are wearing evenly so far. I almost always ran at least 2 PSI above mfr pressure, especially for highway driving. I have the stock Dunlop 18's.

How many miles do you have on your car now? I have the stock Dunlpops.. and at 17.5k they are running thin.. was sort of "forced " to replace the fronts this week...

I only have about 9000 miles. When I referred to even wear, I mean that the tires are not wearing more in the middle than they are on the edges.

People seem to be getting 15,000 to 20,000 miles on these tires. I think part of this is due to the low profile/high performance aspect.