Tire sizes when going with 20" wheels

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Old Jan 23, 2018 | 08:04 PM
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Tire sizes when going with 20" wheels

Hi, I haven't been able to find any recent threads on this... almost all posts on this I could find were for the previous gen car.

So, the current rubber on my car is the factory multispoke wheels 19x8.5 and 19x9.5 with 255/25-19 front and 285/20-19 rear. These have an effective diameter of about 26".

I'm looking at 20" Rohana RC10 for what it's worth. The recommended tires are 255/30/20 front and 295/25/20 rear which are the same diameter.

I'd like to fill out the wheel wells a bit better but I've read some reports that you can't put larger diameter wheel/tire's on the car or you'll have rubbing issue. Is that true? Are the tolerances really that tight already?

I'd like to go 1" larger diameter (0.5" radius) with 255/35 and 285/30 on 20x9 and 20x10.

What tires sizes are others running with 20"?

Did anyone opt to stick with 19" aftermarket wheels rather than go to 20"?
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Old Jan 24, 2018 | 02:34 PM
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I'm guessing wheel swaps are not a big mod amongst members of this forum or CLS owners in general?
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Old Jan 24, 2018 | 07:31 PM
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Many, including myself, put larger diameter 20"s. You can do a search and find all the details. 245/35-20 front and 285/30-20 rear fit without any issues. 255/35-20 is a very, very tight fit upfront and does rub.
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Old Jan 25, 2018 | 02:01 AM
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Originally Posted by threeMBs
Many, including myself, put larger diameter 20"s. You can do a search and find all the details. 245/35-20 front and 285/30-20 rear fit without any issues. 255/35-20 is a very, very tight fit upfront and does rub.
Thanks. I'll try to do more searching, but I had troubles finding anything concrete so far.

I may go with that size... 245/35 and 285/30 will give slightly more profile and a bit larger diameter as you say.

Today I looked inside the front wheel well... I can see the problem, there was only a finger gap between the top of the tire and the strut boot with the stock rubber.

Does everyone with 20s lower the car? I'm guessing so. The fender gaps are almost unsightly as it stands with 19" wheels, I'm sure that 20s will just make the fender gaps look even bigger. Lowering this car seems to be a pick your poison situation unlike just throwing on a set of lower springs as is the case on most cars.
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Old Jan 25, 2018 | 07:23 AM
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245/35 front and 285/30 rear should fit easy. I had a problem with 245/35 front Michelin PS4S tire (rubbing on boot) but fixed it with Michelin PSS K1 tire. Every tire has a bit of difference in the diameter. Still no concrete proof as to why that happened.

As to lowering your car, that's your choice. I keep it at stock height as I would hate to compromise my ride quality. But if I were ever to do it, i would use a lowering module either Lomo M1 or Renntech.
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Old Jan 29, 2018 | 04:11 PM
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Originally Posted by Acidic Reflux
245/35 front and 285/30 rear should fit easy. I had a problem with 245/35 front Michelin PS4S tire (rubbing on boot) but fixed it with Michelin PSS K1 tire. Every tire has a bit of difference in the diameter. Still no concrete proof as to why that happened.

As to lowering your car, that's your choice. I keep it at stock height as I would hate to compromise my ride quality. But if I were ever to do it, i would use a lowering module either Lomo M1 or Renntech.
I found your thread on your tire fitment issues. Wow. It's a bit shocking to me that some tires could have larger diameters than others of the same size. They really need to make their specs accurate.

I'm partial to the Conti ExtremeContact DWS06... I really hope they will fit on mine. I'm going with Rohana RC10 wheels and plan to go with 245/35-20 front (20x9) and 285/30-20 rear (20x10).

I notice that Rohana RC10 come in a few different offsets for 5x112 bolt patterns... for 20x9 on the front they offer 25, 35, and 45. And on the rear 20x10 they offer 18, 33, 45.

Which ones do I want to get that will push my wheels out to the fenders without fitment or rubbing issues?

EDIT: How is the ride on your setup? I'm honestly still debating if I shouldn't just go with 19" wheels to keep the stock tire sizes and just get a better offset to push things out a bit.

If I go with Rohana 19x8.5 front and 19x9.5 rear, they have offsets of 25 and 42 (front) and 30 and 47 (rear)... I think stock ET is 35 and 48 so I probably want the 25 and 30 ET to push things out further. Correct?

Last edited by VirtualRain; Jan 29, 2018 at 05:09 PM.
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Old Jan 29, 2018 | 05:48 PM
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Originally Posted by VirtualRain
I

I'm partial to the Conti ExtremeContact DWS06... I really hope they will fit on mine. I'm going with Rohana RC10 wheels and plan to go with 245/35-20 front (20x9) and 285/30-20 rear (20x10). They fit just fine.

I notice that Rohana RC10 come in a few different offsets for 5x112 bolt patterns... for 20x9 on the front they offer 25, 35, and 45. And on the rear 20x10 they offer 18, 33, 45.

Which ones do I want to get that will push my wheels out to the fenders without fitment or rubbing issues? See in bold
^^^
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Old Jan 29, 2018 | 06:31 PM
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Originally Posted by VirtualRain
I found your thread on your tire fitment issues. Wow. It's a bit shocking to me that some tires could have larger diameters than others of the same size. They really need to make their specs accurate.

I'm partial to the Conti ExtremeContact DWS06... I really hope they will fit on mine. I'm going with Rohana RC10 wheels and plan to go with 245/35-20 front (20x9) and 285/30-20 rear (20x10).

I notice that Rohana RC10 come in a few different offsets for 5x112 bolt patterns... for 20x9 on the front they offer 25, 35, and 45. And on the rear 20x10 they offer 18, 33, 45.

Which ones do I want to get that will push my wheels out to the fenders without fitment or rubbing issues?

EDIT: How is the ride on your setup? I'm honestly still debating if I shouldn't just go with 19" wheels to keep the stock tire sizes and just get a better offset to push things out a bit.

If I go with Rohana 19x8.5 front and 19x9.5 rear, they have offsets of 25 and 42 (front) and 30 and 47 (rear)... I think stock ET is 35 and 48 so I probably want the 25 and 30 ET to push things out further. Correct?
My offset is 32 front and 42 rear and they are not too flush. you can go with 25 front and around 35 rear and itll be perfect.
As for ride confort it was horrendous with 30 & 25 series tires. 35 & 30 improved it ALOT. I removed 18” wheels with 40&35 series tires so maybe i felt it more but factory 19” tires come with 35&30 series tires anyway so it won’t make much difference.
Are the wheels you looking at hybrid forged or forged? If so they will be lighter then oem wheels so it really wont make much difference in ride quality.
If I could do ot all over again I’ll probably stick with 19 with 40&35 series tires for more peace of mind But then again I absolutely love the look of my car and 35&30 series tires are great.
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Old Jan 29, 2018 | 07:20 PM
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Originally Posted by Acidic Reflux


My offset is 32 front and 42 rear and they are not too flush. you can go with 25 front and around 35 rear and itll be perfect.
As for ride confort it was horrendous with 30 & 25 series tires. 35 & 30 improved it ALOT. I removed 18” wheels with 40&35 series tires so maybe i felt it more but factory 19” tires come with 35&30 series tires anyway so it won’t make much difference.
Are the wheels you looking at hybrid forged or forged? If so they will be lighter then oem wheels so it really wont make much difference in ride quality.
If I could do ot all over again I’ll probably stick with 19 with 40&35 series tires for more peace of mind But then again I absolutely love the look of my car and 35&30 series tires are great.
Thanks. I just got an email from Rohana wheels and they recommend the 25 and 33 offset respectively which is consistent with what you guys are saying.

I'm hoping these wheels and tires will fill up the wheel wells sufficiently that I don't feel it looks ugly without lowering. Do you have any pics of your setup (e.g. a side profile) so I can see what it looks like at the factory ride height?

I'm not sure what the factory wheels weigh but these RC10s are apparently around 30lbs each.
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Old Jan 29, 2018 | 07:58 PM
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Originally Posted by VirtualRain
Thanks. I just got an email from Rohana wheels and they recommend the 25 and 33 offset respectively which is consistent with what you guys are saying.

I'm hoping these wheels and tires will fill up the wheel wells sufficiently that I don't feel it looks ugly without lowering. Do you have any pics of your setup (e.g. a side profile) so I can see what it looks like at the factory ride height?

I'm not sure what the factory wheels weigh but these RC10s are apparently around 30lbs each.


My car is at factory height.
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Old Jan 29, 2018 | 09:15 PM
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Originally Posted by Acidic Reflux



My car is at factory height.
Thanks. That looks great.
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Old Jan 29, 2018 | 09:29 PM
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Sooo, I have a set Zito Wheels on Pirelli PZero Nero GTs. Wheels are 20x9.5 and 20x11. I don't know the offset.

Tires are 255/30/20 and 305/25/20.
It looks like the back SHOULD be having clearance issues, but I haven't yet. I've bottomed out more times than I care to remember. Front are zero problems.
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Old Jan 29, 2018 | 10:58 PM
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So I purchased the Ghost Links prior to installing my wheels and tires. Although I could probably lower the car 3/4"-1", I chose not to. It would be Instagram perfect, but freeway ****ty. So I sold the links and am rolling without.
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Old Jan 29, 2018 | 11:48 PM
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Originally Posted by aguilar6222
So I purchased the Ghost Links prior to installing my wheels and tires. Although I could probably lower the car 3/4"-1", I chose not to. It would be Instagram perfect, but freeway ****ty. So I sold the links and am rolling without.
Yeah, that looks pretty damn good as it it. What's your tire, wheel size and offset?
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Old Jan 29, 2018 | 11:51 PM
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Originally Posted by aguilar6222
Sooo, I have a set Zito Wheels on Pirelli PZero Nero GTs. Wheels are 20x9.5 and 20x11. I don't know the offset.

Tires are 255/30/20 and 305/25/20.
It looks like the back SHOULD be having clearance issues, but I haven't yet. I've bottomed out more times than I care to remember. Front are zero problems.
Thanks your offset looks very aggressive - pushing the wheels past the fender in the front. I'm expecting mine to be a bit more tucked in.
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Old Jan 30, 2018 | 12:10 AM
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Originally Posted by VirtualRain
Yeah, that looks pretty damn good as it it. What's your tire, wheel size and offset?
I have no idea of the offset. Tire and wheel size were in my first post, just under the second picture.
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