Tire Pressure Monitor Problems With New Wheels

[trdpower04]

I installed 18" Konig wheels with 235/40/18 tires, and they are all set at EXACTLY 35psi. The damn pressure monitor keeps coming on, then it'll shut off for a while, etc. I read the manual, and reset the system just like it said, and it still does it!! Of course, since they are aftermarket wheels, my dealership won't touch it. But I also had this problem after I blew out a stock tire and had to replace that (a week before I got my new wheels, imagine that...). Does anyone have any suggestions?? Thanks.

[boaclub923]

i'm not exactly sure, so forgive me if i say something wrong.
according to the info that i cathered b4, tire pressure sensor is mounted inside of the facotry wheels. since u change it to aftermarket wheels, the light comes up indicating missing pairing with tire sensor instead of low tire pressure. i don't think there is any way u can get away with it, unless u remove the tire-pressure indictator's light bulb in ur dash, or remove tire sensor from ur factory wheel and mount it inside of ur new wheels.
that's all i konw, hope that info helps.

[michaels artic frost]

i'm not exactly sure, so forgive me if i say something wrong.
according to the info that i cathered b4, tire pressure sensor is mounted inside of the facotry wheels. since u change it to aftermarket wheels, the light comes up indicating missing pairing with tire sensor instead of low tire pressure. i don't think there is any way u can get away with it, unless u remove the tire-pressure indictator's light bulb in ur dash, or remove tire sensor from ur factory wheel and mount it inside of ur new wheels.
that's all i konw, hope that info helps.

What you said is false. I contacted a local Toyota dealership and this is what they had to say.
The tire pressure sensor is connected with the ABS brakes, there's a photo eye sensor that monitors the tire rotation of how fast it rotates, if the rotation is too low then the tire pressure light displays inside your car.

With that being said.

trdpower04,

Your new wheels are running 235/40/18 tires, stock is wheels are running 215/55/17. The diameter for the new wheels is 25.4 inches and your stock is 26.3 inches. That's .9 inch of a difference. Therefore your speedometer reading with non-stock tire is 3.5% too fast. When your speedometer reads 60 mph, you are acutally traveling 57.9 mph.

Use this as a guide.
http://www.miata.net/garage/tirecalc.html

I've got DUBS on mine and my tire pressure light comes on every now and then. I just reset it and it goes away. I've got 245/35/20 on mine and the diameter is 26.8, so I'm only .5 of a difference, which does not make that much of a difference in the tire rotation. Try to keep as close to the stock diameter settings if you want your car to stay within Toyota specifications.

My other concern is the difference in the diameter ratio; keep in mind that through time of traveling with that size wheel, the computer on the car will continue to read your wheel rotation at a different setting then what is recommended. It may have a negative effect on the computer on the car in the long run. (This was confirmed with the Toyota service as well.)

Hope this helps,
-Michael

[DocJohn]

Just as a note: If you are going to go with an 18" wheel, a 235/45/18" tire will bring you within 0.1% of the factory tire's revolutions per mile and would not adversely affect the car's computers and sensors.

This is not a very common tire size, but there some good ones available.

[michaels artic frost]

Just as a note: If you are going to go with an 18" wheel, a 235/45/18" tire will bring you within 0.1% of the factory tire's revolutions per mile and would not adversely affect the car's computers and sensors.

This is not a very common tire size, but there some good ones available.

That's very true, I remember recommending that to someone in another thread, but can't remember what thread it was...lol.

[mattyboyl]

Good info. Mike. I learn something everyday. My tire pressure light actually went on a few times when I travelled to Virginia which is 311 miles from where I live> I checked the pressure and all was good. I don't know what happened there, but it hasn't done it since.

[mtodde]

Good info. Mike. I learn something everyday. My tire pressure light actually went on a few times when I travelled to Virginia which is 311 miles from where I live> I checked the pressure and all was good. I don't know what happened there, but it hasn't done it since.

There have been a couple of posts from people experiencing this and I have experienced it twice myself. Both times the light came on and I could not reset it initially; both times I checked the tire pressures and they were all fine. The next time I started the car it was fine. I have the stock wheels & tires, but I can't speak for everyone. As mentioned above if you have replaced your wheels & tires your system would probably be in alarm all the time and need to be disabled.

I believe that the Solara has the best of the current tire pressure systems - with transmitters in the wheels; there are a number of things that could cause interference with the reception of the signals from the transmitters in addition to actual tire pressure problems. Interestingly Lexus offers this on the LS, but the SC is a cheaper system. There was an article in the Wall Street Journal one day last week on the tire pressure warning systems.

EDIT
I didn't see the part of Michael's post about the tire pressure system being tied into the ABS system. We have the same system as the Lexus SC, which is not as good as the system in the LS.

So most of my post can be ignored...if anyone has WSJ online maybe they could post that article for us - it was in the print edition one day last week in the personal journal section.

[mattyboyl]

You know though, if you get enough false signals, you'll get what I call "the boy who cried wolf effect". I'm sure you all know the story. If your tire warning system keeps enabling even though pressure is fine, one day that won't be the case, and you'll just ignore the light and figure it's another false signal, therefore making what was supposed to save a life, not effective. Same thing with fire alrms in building. You have these jackasses puilling the lever and having the overhead say it was a false alarm. Therfore, if a real fire happens, people will eventually ignore the signal. Toyota needs to perfect this so that it can be as effective as possible. We as humans start to ignore things when there isn't an effect or reward. It's juyst a Pavliovian thing. Soon, we will be conditioned not to salivate when hearing a can opener since every time we come in the kitchen, the damn wife is feeding the dog and not us. Therefore, the behavior of salivating will become extinct. Get it?

[michaels artic frost]

I've got DUBS on mine and my tire pressure light comes on every now and then.

I would have edited my post but thought this would stand out more.

I noticed that my tire pressure light usually comes on when I drive over a rough spot on the road. This occured on one on two instances with my stock wheels as well. However, with my DUBS, it's occuring more so. I usually check the tire pressure to make sure it's okay when I get out of the car, like Matt said, better safe than sorry.

[LukeTheWarrior]

just to add a little tid bit, in the manual it says rapid acceleration/deceleration can trigger it, one of my first nights out with my license it came on (that night I had a full car of teenagers(5) and did rapidly accelerate) I had no idea what the light was since I'd never seen one before and asked my dad who looked in the book and(after we checked the pressure) had a little talk about fast driving he still jokingly nags me about it lol

but my point is with a lot of weight in the car and the acceleration triggered it

[trdpower04]

I realize that the monitor reads off of the wheels speed sensors, but why should I have a problem when they use the same system for the 16" OEM wheels and the 17" OEM wheels? As long as all of the tires and wheels are the same size, the wheels speed sensors should not notice a difference. Right?

[slingshot]

It's the diameter that matters. When moving forward and rolling one full tire rotation, the car goes a different distance with different diameter tires. The Miata link article explains it in more detail I think.

[DocJohn]

I realize that the monitor reads off of the wheels speed sensors, but why should I have a problem when they use the same system for the 16" OEM wheels and the 17" OEM wheels? As long as all of the tires and wheels are the same size, the wheels speed sensors should not notice a difference. Right?

Actually trdpower04 make a good point here.
My research on this sensor system indicates that it detects low tire pressure by looking for a variation in the rotation rate between the 4 tires. If one tire has a lower air pressure than the other three, it will have a slightly smaller diameter and therefore cause a slightly faster rotation rate as detected by the speed sensors that I believe are part of the ABS system.
This explains in part why the tire pressure warning system doesn't work under some of the conditions as listed on page 136 of the Solara Owners Man.
But I can't understand why it would fail to function if all 4 tires are the same size but larger than OEM ones. Perhaps there is also a nominal rotational rate threshold programmed into the system. Any reading above or below the threshold triggers the warning even if all 4 tires are rotating at the same speed.
Perhaps someone out there has a more complete understanding of how this system operates?

[boaclub923]

What you said is false. I contacted a local Toyota dealership and this is what they had to say.
The tire pressure sensor is connected with the ABS brakes, there's a photo eye sensor that monitors the tire rotation of how fast it rotates, if the rotation is too low then the tire pressure light displays inside your car......
-Michael

wow, ha~ i guess i didn't do my research good enough~ ^^;; thx for correction~

[michaels artic frost]

What you said is false. I contacted a local Toyota dealership and this is what they had to say.
The tire pressure sensor is connected with the ABS brakes, there's a photo eye sensor that monitors the tire rotation of how fast it rotates, if the rotation is too low then the tire pressure light displays inside your car......
-Michael

wow, ha~ i guess i didn't do my research good enough~ ^^;; thx for correction~

LOL...np. We're all learning...all da time, trust me...I know...everyday...there's always something new.