Wheel/Tire size upgrade for 18+ Regals

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19GSport

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2019 Buick Regal GS
Hi guys,
Wondering if anyone has upgraded their wheels and tires yet.
I'm looking at 265/40-19 on a 19x9.5 but unsure what offset to go with.
Anyone? Thanks!
 

MelsRegal

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Regal GS 2017
your car came with 245/40x19 tires which are 26.7" in diameter on a 8.5" rim. The 265/40x19 are 27.35" in diameter. An increase of .65" which will slightly effect the speedometer and may effect other speed related computer functions in the transmission if automatic and the ABS/traction control. The tire is almost 1" wider and the wheel is 1" wider. So have you determined if you have a 1/2' clearance to the outer and inner wheel wells? If so measure the current offset and add a 1/2" to it.
 
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19GSport

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The diameter shouldn't be a problem, in fact I definitely want a taller tire just to fill out the wheel well a bit.
The rear appears to have lots of room, but the clearance in front from the strut will be tricky. Not a whole lot of space. I guess I could go with a higher offset that would work well in the rear (+45 maybe) and use spacers up front if needed.
 
975
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2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
Unless you know of someone with EFI-Live to reprogram the ECM to the new tire profile, your gonna regret it. Car will go into limp mode at the slightest bit of wheel spin or slip, and you'll have to stop, turn off car and restart to get it out of limp mode.

HP Tuners still doesn't support our 2818+ Regals. Hopefully soon.

If you have 245-45-18", maybe 255-40-19" will be fine with out tuning. But I could be wrong.
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19GSport

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Unless you know of someone with EFI-Live to reprogram the ECM to the new tire profile, your gonna regret it. Car will go into limp mode at the slightest bit of wheel spin or slip, and you'll have to stop, turn off car and restart to get it out of limp mode.

HP Tuners still doesn't support our 2818+ Regals. Hopefully soon.

If you have 245-45-18", maybe 255-40-19" will be fine with out tuning. But I could be wrong.
I'm sorry, I don't quite understand how the car would by affected by a small 2.2% change in tire diameter, if all 4 wheels have the same change.
Have you had this actually happen?


Edit - 275/35-19 is within 0.4% of stock so that must be acceptable. Not very confident they would fit though!

Edit 2 - The effect of just wear on tire diameter from 100% tread to bald is about 2% difference, so the computer MUST be able to compensate for small changes. I can't see it any other way.
 
Last edited:
975
212
43
S.W. Ontario Canada
Buick Ownership
2018 Regal Sportback - 2010 Yamaha R6 (track bike) Past cars: 92 LeSabre, 98 Regal, 02 GrandPrixGT
I'm sorry, I don't quite understand how the car would by affected by a small 2.2% change in tire diameter, if all 4 wheels have the same change.
Have you had this actually happen?


Edit - 275/35-19 is within 0.4% of stock so that must be acceptable. Not very confident they would fit though!

Edit 2 - The effect of just wear on tire diameter from 100% tread to bald is about 2% difference, so the computer MUST be able to compensate for small changes. I can't see it any other way.
Not me personally,. Friends corvette,. Every time he broke the tires loose at higher speeds his Vette went into a limited power mode.
 
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MPLS
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2018 TourX
This has me reconsidering the snow tire / wheel package I was going to purchase.

I hope there is at least a slight variance as I'd rather not buy another set of 18" wheels and tires as the cost goes up dramatically compared to 16s and 17s.

Does Buick have a reliable tech source where we could dive deeper into this? Or perhaps the dealer would understand how to look into tire size programming?
 

MelsRegal

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Regal GS 2017
or look at www.tirerack.com or do the math ((tire width * aspect ratio) /25.4)*2 + wheel diameter= tire diameter. Once you have the tire diameter for the current tire you plug in the shorter wheel diameter and vary the tire width and aspect ratio to obtain the original diameter. Just dont go too small on the wheel diameter to avoid brake caliper interference.
 
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MPLS
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2018 TourX
That's exactly what I've done here. Tire rack won't even let me select a winter wheel/tire combo for the TourX.

I can get the overall diameter within 0.1" of factory with 17" wheels (235/55R17) or 0.2" with 16" wheels (225/65R16).

When looking at the Opel/Vauxhall equivalent, there are 16" winter wheel packages available for the car as OE. That gives me hope that a 16" wheel will clear the brakes, but I can't prove that as I haven't tested it.

What I also don't know is if the slight change in diameter will affect how the computer manages the AWD system / traction control / etc.
 

BJP1130

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I contacted Tire Rack in regards to the lack of a winter tire/wheel package to which they replied that they have not gotten a TourX into their “shop” to measure the wheel. Once that happens, they will upload the “possible options”.
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Thread starter #13

19GSport

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2019 Buick Regal GS
Has anyone tried fitting 18s over the Brembos yet?
Looks like there's room, 19 inch snow tires are just so expensive 👎
 
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2018 Buick Regal Tour X
DSC_0330.JPG


I got the Insignia brochure. Look at all the official wheel options in Germany.
DSC_0331.JPG
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Bimmer

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Not yet...
Why not simply go to a local tire shop and ask them to try to fit 16" or 17" steelies?

Otherwise, as long as you're buying four wheels/tires the same size, and they don't rub and the offset isn't too outlandish, then the car won't know the difference...
 
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