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Discussion Starter · #1 ·
So I have ordered a new set of 20" HD spinout wheels and hankook 245/40 r20 tires for my gxp. Wanted them in 18" but they are not available with our bolt pattern. Has anyone went with a similar application? I am concerned about the fit. Not a fan of the all rim and no tire look, and don't want to live in fear of potholes. Front looks easy, but there is a slight intrusion into the rear wheel well in the front of both wheel wells. If these don't fit maybe a lower profile tire? Any other easy options? Or do I give up and settle for something else? Thanks all!
 

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Just wondering if your not a fan of the "donk " look why go with a 20 " rim ? If you are worried about clearance issues and go with lower aspect tires for clearance this is what you end up with a car with rubber bands for tires .My opinion would be to stick with an 18" or possibly 19 " rim as a side note I have been in a few friends cars where they swapped out to larger rim and lower aspect tires and the ride suffered .
 

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Discussion Starter · #4 ·
Well the only reason I opted for the 20s is because the wheels I want are not available in 18s, and worse the original tires only have 14,000 on them so I will have to spring for new tires as well. The good news if you wanna call it that is the wheels have been back ordered since 1/16 and theyre telling me it could be 6-8 weeks before they will have them. If I could get them in 18s I wouldn't even consider 20s for the reasons you stated. So in the meantime figured I would try to find out if I am just waiting for something I like that wont fit when it finally gets here. If I can confirm that then I guess I will have to start my search over. Oh joy!
 

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Discussion Starter · #5 ·
Okay will try again. Will 245/40 r20 fit the back of my solstice, or will I have to go with lower aspect ratio such as 245/35r20? Car is not lowered. Opinions much appreciated!!
 

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I'm pretty sure you're going to rub or not fit at all. I will be putting 285/30/20 on the rear wheels I bought and they'll pretty much fill up the whole wheel well.
 

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dcinsc, going with the numbers reported here by you and Heliosky777 the tires you are thinking about buying (245/40 r20) would create a little over an inch increase over the stock 245/45 R18 tires. It's interesting that Heliosky77 said his 285/30 R20's look like they fill whole wheel well because they really should only be a few millimeters taller than the stock rims/tires. Heliosky77's might seem to fill the wheel well more partly because the 20 inch tire/wheel combo has a little less sidewall flex than the 18 inch combo and it lets this combo stay a little taller than stock under load. Essentially, the sidewall is stiffer. If that's true it would let your combo stay a little taller too. Also not all tire brands will have the exact same overall height at a given size. A Goodyear might be a little taller than a Michelin which might be a little taller than a Pirelli ... at any given size.

With all that being said unless you can find someone running the exact tire/wheel combo that you are thinking about it's hard to be sure if it will rub unless you mount them and compress the suspension until it stops.

It does look like you will be very close at the least and if that bothers you, you might want to try a different combo.

Also you never mentioned offset and width. Are these the same as the stock rims? If not this can create problems both front and rear.
 

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Discussion Starter · #8 ·
Thanks for the input. I am not changing the offset or width, and am only concerned with the total diameter. Want to keep as much sidewall as possible but eyeballing the rear fenderwells I think heliosky may be right. So if as you said if someone doesn't chime in with the thumbs up on the exact setup I will opt for the 35, as I have seen plenty of those here when searching older posts. Thanks!
 

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A 245/35 R20 would be a safer bet. It 'should' actually be a few millimeters less than stock in overall height. Post some pic's when you get it figured out. I'm curious to see how those rims look on a Solstice.
 

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I bought CDNite's staggered tire/ wheel combo. Post 1 has lots of pictures. I live in the lowcountry of SC AKA Charleston. I'm not willing to risk any taller of a sidewall on the 20" wheels because the cobblestone streets and such are not friendly to low riders or low profile tire/ wheel combos.

FS 19 and 20 inch wheel set: Sold
 

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You may want to check a tire size calculator site out. This is what one site said about OEM vs the size you're thinking.

The OEM 245/45/18 tire has a 26.63 tire height, and 8.86 tire width.

A 245/40 r20 measures out to 28.68 tire height (a plus of 2.05 height), and 9.65 width.

Also, a tires height and width can be dependent on the tire manufacturers, because there isn't a industry wide uniform measuring system. In other words, two companies can offer the exact same spec tire, and the tires can be different heights and widths.

Plus 20inch wheels will make your brakes and rotors look very small, and the additional gap between the rotor and wheel looks a tad dorky. Though nothing bigger rotors and brakes can't help to alleviate. $$$$

Having said that, I'm still a fan of big tires and wheels.
 

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I just put 20's on mine last month and I absolutely love them. No rubbing, the ride is smooth and they look awesome.



 

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my rears are an inch larger in diameter as well. Rim size does not mean as much as tire size. Most rims will fit as long as tires fit. 245/45-18 is the same dimensionally as 245/40-19 and 245/35-20=26.6 inches. I have 275/45-18 which is dimensionally the same as 245/40-20, which is 1 inch bigger than stock. or about 27.7inches in diameter.
Backspacing is key. If you didn't change that from stock, you will be close. I drilled a hole into the plastic inner liner and used a body clip to gain about 1/2 inch of clearance. My last solstice I did the same and/or cut some of it and melted other parts. The body clip has been a better option thus far.

The tire size is a math equation. 245 is the width in mm, 40 is the aspect ratio of the sidewall to tread width or 40% and the 20 is rim diameter in inches. Don't get me started on the whys of that mix in standard and metric measurements.

245 x 40% =98 mm sidewall. divide that by 25.4 and you get 3.85 inches for one sidewall. The rim is 20inches and has 2 sidewalls to make the diameter. 20 inches + 3.85 + 3.85 = 27.7 inches total diameter.
 

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These conversions are detrimental to braking and handling - to be done only for appearance.
 

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I believe that's the whole point Bill. Bling, Bling.
 

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These conversions are detrimental to braking and handling - to be done only for appearance.
So, people that want bigger wheels and tires couldn't possibly be trying to gain more traction because of increased HP? Yeah, appearance was the only thing I was thinking about when I got 20" wheels.:rolleyes::rolleyes:
 

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I can tell you that there's a lot less slop or play in the steering with lower profile tires than there is with taller tires. plus I have 11" shoes in the back now versus the 9" ones so traction has increased.
 

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Discussion Starter · #19 ·
Thanks all for the help. And yes its all about the bling! I did check out some tire sizing on-line tools and discovered the max diameter wheel tire combination that will fit the solstice without further modification is 26.8" The 245/40r20 comes in at 27.7" according to what I have found on the web. The 245/35r20 comes in at 26.8"so I guess the decision has been made. Now if the wheels ever show up (backordered) we will be good to go!
 

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Just to be sure you understood what I said, it isn't the width that gives braking issues, it is the diameter. It increases unsprung weight and affects braking.

If you just want traction, you could buy wider 18" rims and mount something like a 285-35x18 on them. They call for 9.5"-11" rims, so you'd have to find rims that fit under there and had the right offset.
 
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