I want to upgrade to some 18's but keep the speedo as close as possible. Is 18x8.5 offset 35 for all 4 with 245/40/18's ok for the G or should I be looking for something else. What would happen with the TPMS? Can I get sensors for the new wheels?

 

to upgrade from 215/55/17 to 245/40/18 the speedo reading will be 2.3% too fast so if you're speedo says 60, you're going 58.6.
235/45/18 is basically a 100% match
Good Luck
Marko

 

Thanks.....is the 35 offset all the way around ok?

 

My stock 17's read 3-4MPH off based on my GPS. I trust the GPS to be accurate (Garmin 2620). But when I put on the summer tires/wheels the speedo is right on. I'm running 245/45/18 on 8" wide wheels.

I believe the manufacturer runs the speedo a little off on purpose so when you think you're doing 75, you're really doing 71-71. Less chance of a ticket I suppose. My wife's Saab 9-3 with stock 17's is off by a similar amount.

 

Any recommendations on a good set of snow tires and rims? Also, how would one get tire pressure monitoring capability if one were to get snow tires?

BTW, esfoad - cute dog. Is that a Bichon?

 

Thanks. He's actually a Maltese. He's 6lbs-14oz of PURE POWER!

And for your tire pressure monitoring question, you can either buy another set of TPS sensors or go without. The worst that happens is that the low pressure light comes on but usually only after 30 or so miles of highway driving. At least, that's what happens with my summer rims/tires.

 

So does this sound like a good package. 18x8.5" 245/45/18 +38 offset all around. What if I went with 225/45/18...is there a big difference? Im not really sure what the sidewall markings mean.

 

The marking mean that the height of the tire is expressed as a percentage of the width. So, a 245/45/18 tire would have a "tire" height of 110.25mm, that is tread to rim. A 225/45/18 tire would have a height of 101.25mm. Therefore, the 245/45/18 tire would look taller in the wheel well, filling it better. You'd probably have to drop the suspension for the 225/45/18 tire to look good. I know, some will say you should drop it no matter what . I choes not to drop mine as I wanted the height for the winter. Great plan since we've had NO SNOW here in NJ so far this year. Some of the tire gurus here can talk about circumference, weight and other considerations. I like the look of 18's but it seems that many here prefer 19's, 20's or even larger !