I'm getting an 09 RX350 with all the bells and whistles as a hand me down (mom is getting a Tesla).
My current rig is an 01 Tacoma with a lot of miles so I'm familiar with Toyota reliability and know my way around a car.
The RX is at 115K miles...couple questions...
What should I watch or look out for on the RX? Any Achilles heels? ~115K miles is often when these things start to show.
Second, it's due for tires. I do a lot of driving on unmaintained dirt roads and would like a mud/snow tire with a strong sidewall (lots of sharp granite), hopefully go up a size to 235 if possible for ground clearance?
I'd like a bit more off road look and capability but I won't use wheel spacers, strut spacers, etc.

 

Wow, that's great......Since it was your mom's, does she have any paper work of what was done? Like you mentioned, being a Toyota product it is reliable. Being that the engine is transverse....east/west, means that its tougher to get to some parts, w/p, alternator, p/s pump, bank 1 plugs/coils, steering rack, ect. If you have no idea what was done, I'd change out the trans fluid, filter as well as the rear diff & trans case, A qt of 75-90 each & a gallon of Maxlife w/ a Wix trans filter as well as clean the two magnets in the pan. Sounds like you have 17'' wheels, which going w/ the 235's would work. At those miles the plugs should of been changed awhile ago. If not, I'd at least replace the bank 1 coils as well. I'd for sure swap out the oil cooler lines for steel lines, such as Dorman offers.....I'd also swap out the vvti oil line on bank 1, as its spiced w/ a rubber line, but bank 2 is a solid metal line, why I have no idea...

 

Going from a 225/65/17 to a 235/65/17 isn't going to raise the car very much.

The 225/65/17 has a side wall height of 146.25 mm while the 235/65/17 has a side wall height of 152.75 mm. The difference is 6.5 mm or approx .255 inch.

If you don't want to do any suspension modifications, about all you can do is go to a larger rim such as maybe 20 inch. But when you go to a larger wheel. you have to be careful that the wheel won't rub the fender. I don't know if my maybe 20 inch example would fit or not.

 

My mistake, it has the stock 235/55R18. I found an old thread that people go with 255/55R18 without spacers or rubbing: https://www.clublexus.com/forums/rx-...55-18-a-6.html
The 255/55 is about 0.8" greater diameter and width.
I'm used to an old, beat-up, 4wd Tacoma with 31" tires so the RX will take a bit of adjustment on my end. The slightly larger all terrains should help. Only other upgrade on the list is some WeatherTech rubber floor mats.
I'll do some digging on the suggestions...had no idea about that vvti oil line but a quick google and I see why.

 

Being that the oem style 18 is 7'' wide, that'd possibly be the narrowest a 255/55 that'd work....I'd think it'd work better w/ a 8''-9'' width wheel....btw Discount tires offers a few wheels...TSW & Legend 5's....I went w/ TSW's w/ a 20mm offset.....Yeah it is totally different than what I'm used to as well...It doesn't like to be hustled in the corners, but it is smooth & reliable & my wife <3's it as a couple of her g/f's have rx's as well .....The 2gr pulls it right along thou.....Not near as a srt8 Jeep, which she mentioned was to stiff riding. Hitup a Lexus/Toyota dealer for the bank 1 metal vvti oil line, I went w/ a Dorman oil cooler line kit. Last Monday morning I replace the convertor after the Y-pipe w/ a 2.5'' Magna flow convertor as well as replaced the muffler w/ a 2.5'' 4''x9''..19'' case length, Dynamax super turbo muffler using 2.5'' piping, leaving the resonator on......Mileage went up as well as a tad bit more throttle response.

 

Since the op has the 18 inch wheels, I'll throw the sidewall height numbers out here for grins & giggles.

The 235/55/18 has a side wall height of 129.25 mm while the 255/55/18 has a side wall height of 140.25 mm. The difference is 11 mm or approx .433 inch.

FWIW, I am running 235/60/18 on my car to get the speedometer accurate. It registered fast with the 235/55. Doing the sidewall height on this tire comes back with 141.0 mm or approx .551 inch - the biggest of the 3.

Felix's thoughts on the rim width for a 255/55/18 tire had me wondering about that as that could be a valid point. Looked it up and that tire is spec'd for rim widths 7 to 9 inches. The 235/55/18 and the 235/60/18 tires have the same rim width spec of 6.5 to 8.5 inches.

 

Lots of new things to learn...here I thought I knew my way around a car.
So this new to me 09 350RX does have a transmission dipstick...whew...glad that's there. The non-dipstick tranny is not DIY to do oil changes...
The 110K mile service was done by Toyota a few months ago. They did not change the ATF and it is a bit dark red on the dipstick. The level is also high. The engine is cold and the level is well above "hot", almost to the "WS" stamp. I'd assume Toyota would've checked those levels...but regardless it makes me wonder as I've been reading about these transmissions and it sounds like the levels must be very precise (or is this just for 3rd gens without a dipstick?).
Are these 2nd gen transmissions susceptible to hesitation or problems and do they need extra care? Another thread mentioned Toyota Lubegard additive helps a lot in those problem instances.
Stick with WS ATF or go with synthetic?
I'll be doing the tranny, transfer case, rear diff oils, plug magnets, and tranny filter as Felix mentioned.

Regarding tires I'm leaning toward the Falken Wildpeak AT3 in 255/55r18. Rated for 7-9" wide rims as Dennis says so the stock 7" should be fine.
FWIW the Wildpeaks are what I've run on my 4wd Tacoma for the past 40K miles. Good all terrain tires. Always ran BFG TA KO which are great but much heavier.

 

The 5-spd trans is a great reliable trans....Really super smooth shifts, unlike I'm use to. There are a few different threads on what trans fluid to use. After a little research, I went w/ a gallon of Valvoline's Maxlife, a Wix trans filter as well as 2 qtrs of Royal Purple's 75/90 diff oil. I've read many do a drain 'n fill.....But not knowing how much debris the magnets collected, I wanted to swap out the trans filter as well as brake clean the magnets & pan, then possibly next time do a drain 'n fill......3.7 qtrs is what the spec's say, but I let it drain while I drained the rear diff & transfer case. I ended using the gallon. A quart for the rear diff & transfer case........

 

well one thing is spark plugs need to be changed out at 120,000 miles. The front ones are easy peasy; only takes about 15-20 minutes to do the front ones. the back ones however; are a royal pita! the rear ones can take 3-4 hours to do. It might not be as long if u know some tricks, etc. It usually requires the wipers and wiper cowl to be removed etc. Do a search of these forums and there is a great thread with pics etc

 

also yes like some of the others may have pointed out; do a trans flush and fill which should be done every 30,000 miles. make sure the replacement fluid is synthetic.

 

The Valvoline Maxlife is a synthetic fluid which is rated for Toyota/Lexus for WS & T-IV as well as other vehicles & I'd also replace the trans filter w/ a Wix & brake clean the magnets at least for the 1st time....Then 30K afterwards you can do a drain 'n fill for the next time....

 

Welcome to the forum.
Steering racks can leak, particularly under passenger side. Rear bank vvti and oil cooler line near oil filter (if equipped) should be replaced with improved all metal parts. There's tons of knowledge in these forums if you search around.
Pretty interested in this larger tire idea you have. If it works out, please post pictures.

 

i think the car will be dependable given you have first hand knowledge of its history. Routine stuff like brakes. I had the radiator changed out, bearings replaced. The big thing though was the transmission at 150k. The research I did said you can expect it. But, then good to go another 150k. I loved mine. Ran like a top. In the end, at 167k, It sacrificed its life for me and my 2 girls.

 

I've got 218k on my 2009. Bought it new, it is our second RX. Previous was a '99 that we put 175K on before selling. Outside normal maintenance I've put an alternator in it at 150K, water pump at 180K, CV joints at 190k (boot was cut so I replaced the whole assembly) and another alternator at 205K. I chalk the alternators up to the Texas heat getting to them but overall this is the most reliable car I've owned. It's also not that bad to work on, no salt/snow in Texas helps. Underside of the car looks like new. I'd say given your mom likely didn't drive it hard your good to go for a while.

 

Find a set of 15" rims from 1998 Jeep whatever. Should be the same 114.3mm bolt pattern. Then you can put lots of rubber (Sidewall height) on there. Might look pretty cool / retro too.

Check the inside of your existing tires for oil / wetness. The struts like to go out on these.