Craig,
Like VB Denny, I think the cabin filter may be difficult to get to on the 1st gen ls. Mine is 99 and is easy change located behind lower glove box. Check your lower glove box and see if you can remove a snap off peice of plastic that attaches; behind this you may be able to see the blower assembly and possible filter location. This is where the 98-00 filters are; they just pull out and is easy replacement. I know there was disscussion on this earlier but I can't remember plus the loss of data base data has us all in the dark.....
On the tire issue.. I'm still looking too. I've got 5/32nds left so I'm not desperate yet plus the Yokohoma's are very quiet which is my requirement (Isn't it everybody else's too!!!)
The Yoko AVS dB S2 have solid ratings and everyone agrees they are quiet ($101) . A tirerack rep also thinks the Sumitomo HTR is real good tire for the money - $61 each! But, I don't know. Then there's the ContiExtreme, Dunlop 5000's, and Michelin MVX4's. So, after shipping (or buying local) you can spend $330 - $550 for the tires plus $100 for alignment. A lot of dealers (and trustworthy insiders) have told me the Michelins are the best. If that is so, then I suppose the extra $200 is gonna be the best money spent once your in the car.
On the other hand, every time I ask about tires for my 99 LS, the shops all come back with a T rated tire. Even a very reputable import (lexus/Acura) shop says they put plain vanilla all-sason (T rated) touring tires on the LS ALL THE TIME!
It's very confusing - Let me know about the valve adjustment !