I just got new wheels. The specs are F 245/35-19x8.5 and R 275/30-19x9.5. I got the tires like that but I was thinking of switching them to 245/40 and 275/35. Do it or I be fine with those. Since I got those wheels I got the tire inflation thingy. Give me advice, check the tire size calculator. Thank you.

Give me advice!!!!
http://www.miata.net/garage/tirecalc.html

Both are off by a smidge, but some do it anyway and deal with the speedo error. Your call on that.

As for the light, you need new TPMS sensors installed and reprogrammed, or just move them over from your OEM's.

^^
what soundmike said. did you get your tpms sensors installed on the new wheels and get them reprogrammed?

^whs, i switched over to orange electronics AM sensors which has a lcd screen (all for ~$100 back then) which shows exact pressure and temp in each tire, so its MUCH more useful than the OEM sensors.

Your call really on both issues, wont have any real affect on the car, ppl have been driving without tpms for 100's of years and now all of a sudden its become a necessity... oh how dependent we have become...

Actually I traded my stocks for these 19"s. What can I do now?! Any aftermarket out there?! The orange light bothers me.

you can get some at like wheel works or Americas tire but putting them on would involve removing the tires and balancing them.

Damn!!! Sound like $100!!!

did you get the wheels from another g owner?

Yeah!!

if those wheels accept tpms then they could of left it on the wheels and all you have to do is get them reprogrammed

Okay! I bet they there then because I saw when they swaped them!! Thank You KURO!!! I just saw my G rolling and those tires looks pretty good!! I just gotta get a wheel alignment!

Another question! How do I know if they have TPMS?!

Best way is to unmount the tire and check. Some would say that if you have metal stems that you have the sensor, but some aftermarket wheels come with metal stems (like my Ray's, for example, and i haven't had a TPMS sensor on it for years).