18 x ?? w/?? offset
19 x ?? w/?? offset

Anyone know?

18 x ?? w/?? offset
19 x ?? w/?? offset

Anyone know?

19x8 +48

I'd imagine the 18" is 18x8 +48. Can't say for sure though since I don't have them.

18 x ?? w/?? offset
19 x ?? w/?? offset

Anyone know?

The 18's are:

18x8 (45.7 cm)

19x8 +48

I'd imagine the 18" is 18x8 +48. Can't say for sure though since I don't have them.

Excellent, thanks. :thumbsmileyhere:

Anyone with the 18's have a chance to get them off and/or get a look at the stampings on the inside of the wheel, including the offset?

Sandog, the 19" wheels have a 5 X 120mm bolt pattern and a 40mm offset. I don't know for certain whether they are 8" or 8.5" wheels. But a 19 X 8.5 with a 40mm offset fits fine (that's what I got for my spare).

Sandog, the 19" wheels have a 5 X 120mm bolt pattern and a 40mm offset. I don't know for certain whether they are 8" or 8.5" wheels. But a 19 X 8.5 with a 40mm offset fits fine (that's what I got for my spare).

It's a +48 not +40 and they are 19x8.

Unless I am reading the inside of the wheel incorrectly.

It's a +48 not +40 and they are 19x8.

Unless I am reading the inside of the wheel incorrectly.

The inside of the wheel is the gospel here. :us_flag:

It's a +48 not +40 and they are 19x8.

Unless I am reading the inside of the wheel incorrectly.
Well, I assume you know how to read, so I stand corrected! :p

Guys, all we need now is for someone to put their G8 on a lift and take measurements between the outside edges of their wheels/tires and we will be able to see what offset (a computation of backspace and frontspace) would be needed for perfect fitment of the most tire possible under the wheel wells of the G8.

Backspace of the stock wheel is established by the diagram below (6.4"); now all that needs to happen is for someone to measure the inside space between the wheel/tire in the rear, to the nearest suspension components, to find the additional backspace available.

Also, the same can be done for the space on the outside of the wheel/tire to establish how much 'frontspace' (this is what it is actually called), and between the two measurements, we will find out exactly how much tire we can squeeze back there.

:gears:

http://g8board.com/forums/attachment.php?attachmentid=836&stc=1&d=1208916125

:search: The offset for both 18" & 19" is +48mm. Both are 8" in width. Thank you for playing.

:search: The offset for both 18" & 19" is +48mm. Both are 8" in width. Thank you for playing.

Yeah duh. So how much additional backspace and frontspace do you have before you hit the max that fits under the rear wheel well? Hello?

Go to the end of the line. :nono:

Yeah duh. So how much additional backspace and frontspace do you have before you hit the max that fits under the rear wheel well? Hello?

Go to the end of the line. :nono:

You only asked for the stock wheel specs. For info on the available amount of room in the fenderwell, go here (http://www.g8board.com/forums/showthread.php?t=2262). :ohsnap1:

You only asked for the stock wheel specs. For info on the available amount of room in the fenderwell, go here (http://www.g8board.com/forums/showthread.php?t=2262). :ohsnap1:

Dude, it's my thread, I can choose to enhance, embellish, or eliminate it altogether. For this thread, I chose to expand its purpose.

You want free reign? Start your own frickin' thread. :fawkdance:

Dude, it's my thread, I can choose to enhance, embellish, or eliminate it altogether. For this thread, I chose to expand its purpose.

You want free reign? Start your own frickin' thread. :fawkdance:

If I wanted free reign, I would have had a G8 in my shop & figured out what would fit already. :slap:

Mr. Sandog: That tire/wheel calculator beats the one I use by a mile. Can we get a link? Thanks!

question anyone hear now what the stock wheels weigh

Mr. Sandog: That tire/wheel calculator beats the one I use by a mile. Can we get a link? Thanks!

Linky (http://www.1000rims.com/rt_specs.jsp)

Sandog, here are the specs from my stock 18" wheels. 18x8 with 48mm offset and 6 3/8 backspace. I put 19x9.5's on mine with a 45mm offset and 7" backspace. You still have a ton of space between the tire and suspension on the 19's. Its very hard to measure under the car laying on the concrete, but, there is approximately 2"s between the tire and inner fender well. Hope this help.

Sandog, here are the specs from my stock 18" wheels. 18x8 with 48mm offset and 6 3/8 backspace. I put 19x9.5's on mine with a 45mm offset and 7" backspace. You still have a ton of space between the tire and suspension on the 19's. Its very hard to measure under the car laying on the concrete, but, there is approximately 2"s between the tire and inner fender well. Hope this help.

Interesting....so it looks like a 10" or even a 10.5" wheel could fit with a 50mm to 55mm+ backspace...maybe we're looking at the possibility of sticking 305's back there. Awesome!!!

I would think that you wouldn't need anymore offset, just more backspace. A 10" would be just right with a 45mm offset and 8" backspace and maybe a 305 would work. Good luck, let me know if I can give you anymore info. Its a very big caliper in front, so, offset is real important up there. I've got about 3/8 inch clearance on the caliper and probably 1" on the strut tower, my wheels in front are 35mm offset with a 6" backspace.

With those specs on a 9.5" wheel, how does it sit to the outer edge? I'm looking at some 9.5" wheels with a 40mm offset and am trying to figure out how they'd look.

Sandog, here are the specs from my stock 18" wheels. 18x8 with 48mm offset and 6 3/8 backspace. I put 19x9.5's on mine with a 45mm offset and 7" backspace. You still have a ton of space between the tire and suspension on the 19's. Its very hard to measure under the car laying on the concrete, but, there is approximately 2"s between the tire and inner fender well. Hope this help.

The stock wheel (18") with tire weighs 54 lbs. I didn't weigh my new ones, but, I will later today. I bet they will weigh about 60 lbs. (19x9.5) or maybe slightly more. I was taking pictures from the side for you but my batteries went dead, check back in a little while and I'll post so you can see the tire/wheel from side. It sets just inside the inner lip of the wheel well.

Interesting....so it looks like a 10" or even a 10.5" wheel could fit with a 50mm to 55mm+ backspace...maybe we're looking at the possibility of sticking 305's back there. Awesome!!!
Forget that. Bring on the 345/30R19s from the Viper. :yumyum: Being realistic, I'd bet a 315 would fit easily

I would think that you wouldn't need anymore offset, just more backspace. A 10" would be just right with a 45mm offset and 8" backspace and maybe a 305 would work. Good luck, let me know if I can give you anymore info. Its a very big caliper in front, so, offset is real important up there. I've got about 3/8 inch clearance on the caliper and probably 1" on the strut tower, my wheels in front are 35mm offset with a 6" backspace.

You forget something in your offset calculations. If the wheel gets wider or narrower, the offset will change no matter what. If you make the factory 8" wide wheels wider, the offset will change. I'm gonna try to explain without confusing anyone.

If there is 2.5 inches of space inside the wheelwell with the factory wheels on, & you put a wheel that is 2 inches wider & it all needs to go into the wheelwell, then backspacing will be the easiest number to come up with. The factory wheel has 5.89" of backspacing. So, the replacement wheel would need 2 more inches on the inside of the wheel so not to stick the wheel & tire out from under the fender. So, if you do the calculations, that 10" wheel (w/ 7.89" BackSpacing), it's offset will change to +73mm. I've attempted to make a diagram for a visual aid.

http://www.g8board.com/forums/attachment.php?attachmentid=862&stc=1&d=1209306732

Here ya go.
http://www.cardomain.com/member_pages/show_image.pl?bg=FFFFFF&image=http://memimage.cardomain.net/member_images/1/web/3049000-3049999/3049754_30_full.jpg
http://www.cardomain.com/member_pages/show_image.pl?bg=FFFFFF&image=http://memimage.cardomain.net/member_images/1/web/3049000-3049999/3049754_33_full.jpg
Then a picture from a distance.

I'm not sure where you got the 5.89 backspace, I measured my stock 18" wheel and it 6 3/8 backspace. However, I have never seen a wheel with a 74mm offset, nor have I seen one listed. I do agree that if you add an inch in width that the offset changes. My new wheels are as follows. 19x8.5 with a 35mm offset and 6 inch backspace. The rears are 19x9.5 with a 45mm offset and a 7 inch backspace. They fit under car just fine and could definetly use a wider tire. I changed from my original 285-35 to a 255-40, I wish now I would have stayed with the 285. Thanks for your diagram.

I'm not sure where you got the 5.89 backspace, I measured my stock 18" wheel and it 6 3/8 backspace. However, I have never seen a wheel with a 74mm offset, nor have I seen one listed. I do agree that if you add an inch in width that the offset changes. My new wheels are as follows. 19x8.5 with a 35mm offset and 6 inch backspace. The rears are 19x9.5 with a 45mm offset and a 7 inch backspace. They fit under car just fine and could definetly use a wider tire. I changed from my original 285-35 to a 255-40, I wish now I would have stayed with the 285. Thanks for your diagram.

I got the 5.89" backspacing by adding the offset to the rear half of the wheel (centerline to rear edge of the wheel). 4" + 1.89" (48mm divided by 25.4). I bet our differences are from where we are measuring. You probably measured from the rear lip to the mount pad. Most wheels are measured at the inside of the lip where the tire sits. So, the factory wheel is more like 8.5" measured from front edge to rear lip.

You are probably right. Thanks for the info. Its all good and we are all just trying to help each other out and keep someone from making bad decisions. Most of us are just learning about these rides. I'm probably a little older then most on this forum and after drag racing for 15 years and having owned over 65 cars and trucks I'm still learning about all the new ls motors and trannys. I'm old school when it comes to the new wheels. You look at my truck its all tucked up under the fenders, my prostreet malibu and nova was tubbed with 15x14's with 3 1/2 inches of backspace, none of this stuff with offsets. This metric **** with offsets just came about with the front wheel drive stuff. Now that all the companys are pushing the axles and front spindles farther out towards the fender well lip, its definetly critical to get both the backspace and the offset correct. I think everyone learns something on this forum everyday and I appreciate everyones input when I thread something new.

Question everyone. I just got a new set of sensors part number 15922396 got installed and went to dealer and they tried putting in learn mode and than using the tire wand and couldnt get to work. The sensors coudlnt be matched. Do you have to enter the part number in somewhere in the DIC mode with the GM computer they hook up via OBD2?

Question everyone. I just got a new set of sensors part number 15922396 got installed and went to dealer and they tried putting in learn mode and than using the tire wand and couldnt get to work. The sensors coudlnt be matched. Do you have to enter the part number in somewhere in the DIC mode with the GM computer they hook up via OBD2?

You are more likely to get an answer to your question if you start your own thread with your topic in the title.