I changed my stock wheels to 18''. After a bit over 24 hrs the Tire Pressure light came on. The tires are fine. Is it safe to reset the light? Or should it be looked at?

Do you have the TPMS in the wheels that are on the car? If not, that is why the light in your dash is on, and you cannot get it to go away, without putting the sensors in your wheels. If the sensors are in your wheels, and the pressure in them is lower than your stock wheels, then you need to reset them to the air pressure in the aftermarket wheels. Yeknow?

^^^ what he said. it sounds like you dont have sensors installed, as lower profile tires 99% of the time require higher PSI than a higher profile, like the stock tires. im not sure if the system is setup to trigger the light if the pressure is above a certain range or not. all i had done with my 17s was have the sensors swapped, the tpms system did not have to be reset or anything else... just move the sensors over.

The wheels do not have the sensor. I'll have to move the sensors over or get new ones I guess.

just move them, it will be much cheaper. those things are expensive

Well hopefully they still have access to the old tires so they can get the TPMS. If not then you're going to have to buy new ones (ouch!) and have them programmed to the car.

I have the old tires/rims in the basement. Anyone have a guesstimate how much that switch will cost? Will the Scion dealership even want to do it?

you should only have to pay for mounting and balancing again, which is usually $10-15 a tire. not sure if/who may also charge a little extra to swap the sensors.

im not sure if the scion dealership would want to work on aftermarket rims. they may though, youd have to call.

Did you mount the new tires yourself, or have a tire shop do it. If you had a shop do it, they should have swapped them as part of the deal.

I'm assuming that since my light is not on, my wheels came with the sensors (dealer installed). My question is. Did they adust the sensor or computer to accomidate the lower profile tires? Running 225/40zr/18's

And any idea what the tire pressure should be on this tire?

i asked the local tire shop if theyd mind swapping the sensors/stems over to my new 18's when i get them and they said they could pull the tire edge down on both tires and swap they with out having to remove tires, so no rebalance charge, said it would be 50 bucks. in the event that the new rims that you may buy, for those shopping the market, there are kits you can use in the event the new rims wont accept the sensor due to size/shape constraints.they mount the sensor inside the tire around the rim on a band. ill prob have to reset the system due to the low pros i got though.

If your tires are balanced, then you put the TPMSensors inside the wheels that are already balanced, you are going to have to re-balance them!

TP sensors are now federally required. Every 08 (including installs of aftermarket stuff by dealers) has some system or another.

The owner's manual has a good description of how they work and how to reset the system if necessary. (e.g., if new tires that run at different pressure etc) Don't know if there's an upper limit, but I suspect it would be well out of the reality range if so.

Yup, they're heavy enough to require a rebalance (about the same as smaller balancing weights).

I didnt even think to look at the manual. Figured it wouldnt tell me anything I guess.

Thanks for all the info.

guess ill have to get them re- balanced. was hoping they tpms stems were close to a normal stem weight.

Had new 17" wheels put on my 09 XB, they swapped the sensors, the light would flash for 1 minute and then stay on. It would not reset! Took it back and they got a meter to check them. All the sensors are sending a signal, but it will not reset. They said I had to take it too the dealer, so I told them they said they would work before I purchased the tires! I made them break down the tires and give me all four sensor numbers off the wheels and then re-balance them. This way when I take it to the dealer I wont have to pay them to pull off the tires to get the number. So now I will wait for the fist oil change and see if the dealer will take care of the light. What a pain in the arse!!