Topic: Fitment questions between stock 18" rim and 20" rims

[KWhale]

OK, so I've been researching getting a set of 20" rims for my 2007 GXP.  The rims I like come in the correct bolt pattern, and size I want, but the offset is too low, and not wanting to go the custom route, I decided to see what affect the low offset actually has.

Just to get everyone on the same page, our stock Solstice rims are
18x8, 5x110 bolt pattern, with a 55mm offset on 245/45/18 tires.
The rims I want to try are
20x8.5, 5x110 bolt pattern, with a 34mm offset on 245/35/20 tires.

OK, before you beat me up, I know the only real issue with these rims IS the offset.  So, not being all that knowledgeable at tires and rims and offsets, I did some research.  I found a great site for fitment calculations, and I know they are not a vendor here, but their prices are all higher than our supporting vendors, so I thought it would be OK to post a link to their Tech Section.  If you go to the link below, you can use several of their calculators to play with rim and tire combination's to see what might fit on any car.  The link to get there is http://www.1010tires.com/tech.asp and I was going to the "Sizing" sections.

So the tires and rims I listed above, when fed into their calculators, told me that they would fit on my car, and the speedometer would be within 2% (showing too slow).  So I was happy so far with the research.  Then I went after the offset to see what effect a difference of -21mm would do.  I went to the Offset Calculator section of the above provided link.  When I plugged in my numbers, here are the results.

Inner Clearance results in 15 mm more space between the back of the rim and the center line.  So far so good, there would not be any interference with brake calipers etc.

NOW THE PART I NEED HELP ON:
Outer Position results in 27 mm more rim sticking out than stock.  In other words, the outside of the tire would stick out of the wheel wells by an additional 1.05 inches.  While 1 inch seems small in many areas (insert joke here!) a difference of 1 inch when it comes to the tires of a car could be huge, I don't know.  Will the front tires have enough clearance to turn in and out while hitting bumps at the same time?  Will the tires in general hit the inner liners when going over rolling or bumpy roads?  And this is where I'm stuck.  I have no idea if this measly 1 inch is too much or not.

Does anyone have any experience with 20" rims and fitment along the lines of what I'm trying to do here?  Good or Bad?
Do any Tire Guys have knowledge about doing this that indicates it will or will not work for sure on a Solstice GXP?
ANY suggestions that would help, keeping in mind the 34mm offset is carved in stone for this discussion because the manufacturer I want to use only has this offset available.

Thanks, and sorry this post was a little long, but I wanted to make sure everyone knew exactly what I was trying to do!

[KWhale]

Bump for my questions....somebody must have done some wonky offsets on their car.

[DeepBlueGXP]

I have 42mm offsets and the are flush with the outside of the fender.  One of the guys in So Cal has 20" on his and he sometimes hangs with madmods.  It is a sly

[compression]

I have had 18s,19s,20s, and now I have 22s. All fit with out anyproblems except for the 22s. Had to remove some plastic from the rear wheels, and make the car wider in the rear by 2inchs.

[DirtyMike]

i have a 37 mm offset on my wheels, all gravy

[KWhale]

Mike, can you tell me what the size of your rims are too please?  Did you stick with 18, or go with something larger??

[DirtyMike]

18's i really wanted 19's but not much out there

the tire vendor on the big board posted this: According to our guide you can run a 34-65mm offset on an 18x8. The stock 18" wheels have a 55mm offset. These would sit out almost .75" further than the stock 18's.

[KWhale]

Thanks Mike, and I agree with you about the "not much out there".  I've been looking for months, and while there are quite a few options, most of them are not the look I want.  I'm a little old school, so I want pure chrome, and was hopping to go staggered with 18x8 minimum up front, and 18x9 minimum on the back.  I ended up looking at 20's because there were some rims I like in that range, but I'm thinking just stick with 18's now....and to keep searching for another year probably.

[solstice-d]

How can one find out about which ones are the offset pair? Thank you.

[shabby]

In other words, the outside of the tire would stick out of the wheel wells by an additional 1.05 inches. 

Not really, the stock tires are far from the wheel wells. Go take a ruler to your tires and add an inch, you'll see they'll probably be flush with the wheel wells.

[KWhale]

You're right shabby, that part you quoted me on was worded horribly.  I meant to say that the wheels would be 1.05" further out when compared to the stock tires with stock offset.  I have no idea if that would mount them flush with the wheel wells or not.  Very poorly worded on my part, so it's back to the 1 room school house for me for the summer!!