Chargedmr2

My searching skill probably let me down here, but is there a consensus on a good air pressure for tire wear on the IS350?

I just replaced the stock ER33s (didn't like them at all) with Michelin Pilot Super Sport tires--stock wheels and sizes. I just had the car at the dealership for some warranty work and they returned it to me with 45psi in the rears and 40psi in the fronts. Does this seem high? My old ER33s wore heavily on the inside AND outside for the fronts with 35psi. But my rears actually showed wear in the middle (over inflation) with 38psi. Interestingly, these are the recommended pressures as posted on sticker in the door jam. Seems like Lexus got it backwards, at least in my case with the Bridgestones. I don't want to repeat any wear issues with my new Michelins, so any advice will be appreciated.

Sango

iTrader: (10)

Should be about 38-40 psi front while rear is 36-38 psi.

If you do less city then you could make it 36-38 front and 38-40 rear.

Lexus recommends lower for more performance. If you longevity you need need to raise the pressures which I mentioned above.

Also would want to get your geometry and alignment checked as well.

Chargedmr2

Thanks for the follow-up here. By chance, have you had relatively even wear across your tires with these pressures?

I think I'll leave the fronts at about 40 and drop the rears down from 45 to about 36. Hopefully that's not too staggered between the front and rears.

Sango

iTrader: (10)

With the pressures and proper alignment, the wear is wearing normally with the stock suspensions.

To clarify, the front tires is showing outer cupping and the rear is wearing evenly. This is wear is expected as per my alignment tech and I get my tires 4-5K for the tech to monitor the tire wear.

Noeh

iTrader: (3)

Why do you recommend higher front tire pressure for city driving? Will that give you harsher ride?
Thanks

Sango

iTrader: (10)

I'll just repost the answer from another thread. The higher preasure would stiffen up the ride a bit however you do get the longivity; unless you're looking for performance, then a lower and different of numbers would be used.

albatros83

I ran my Pilot Sport A/S at the recommended pressure inside the door (can't remember what it is offhand), and the edges wore much, much faster than the insides, and that was with relatively sedate driving habits. I was so alarmed that I bought an analog dial pressure gauge and had it calibrated and characterized (charted the actual values that corresponded to the indicated values), and kept the pressures where they should be, +/- a couple of PSI depending on temperature. (Hot air = higher pressure, cold air = lower pressure). That was after the first year (10k mi), but I still had excessive wear on the outsides while the insides looked great. So the second year I started running 40PSI all the way around, and the wear pattern improved significantly from just that extra 3-5 PSI. I would have run higher, but that was the max pressure for the tires IIRC.

I just put on a set of Pilot Super Sports Summers today, and I'm going to do the chalk test (http://www.ehow.com/how_6948382_chalk-tires.html) to verify that I'm getting even contact at 40PSI. I still expect the outer edges to wear more quickly on these new tires simply because I plan to do more spirited driving with these sticky monsters, but at least I hope not to have underinflation as a contributing factor.

IMO, the only reason to run a lower pressure is to soften the ride, so that's the only reason I can think of why Lexus selected the pressures they did. But there are better ways of accomplishing that, like stepping down to a 17" rim with higher profile tires, or even 16" if you're feeling particularly grand-fatherish. Might as well throw some whitewalls on there while you're at it. But if a soft ride was your priority, then you probably wouldn't have bought an IS.

It could also be that Lexus' pressure recommendation is based on someone of average Asian body size rather than my fat ***, and I'm just making the tires bulge. Hah. Only kidding. I hope!

phillimt

lexus does love making their tires soft...