National Speed: 2009 Cadillac CTS-V - Fitting a 325/30R19 on stock wheels...
05-12-2010, 03:16 PM
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National Speed: 2009 Cadillac CTS-V - Fitting a 325/30R19 on stock wheels... A new customer of mine purchased a 2009 Cadillac CTS-V brand new, and was tired of the factory 556bhp and the CTS-V factory wheel spin. So in preparation for increasing that factory horsepower output, we needed to figure out a way to increase traction.
The plan I came up with after multiple measurement and theory appointments with the car on the rack:
- Move factory 19 x 9.5 wheels with 285/35R19 tires to front
- Supplement with 5.50mm spacer (this does not need to be hub-centric, as the hub-centric lip extends 11.50mm deep)
- Have factory front 19 x 9 wheels widened 2.00"
- Order custom lug-incorporated 31.75mm spacer (i.e. so this will bolt to the hub, then the wheel will bolt to this). I looked into having custom ARP lug studs made, but to hell if I was going to sell my customer $1,500 worth of lug studs. This was the most cost-effective route. Please note, I ordered these spacers with the intent of them being too large so we could mill them down to fit.
- Install 285/35R19 Nitto INVO on the front location
- Install 325/30R19 Nitto INVO on the rear location
And somewhere in between, burn the rubber off the stock rear tires.
The first test-fit spacer and tire came in for test fitting...
5.50mm front spacers fitting...
And lug-incorporated 31.75mm in the rear...
Fitting...
Fit perfect...
Now, to take care of these stock 285/35R19 tires in the most fun way possible...
Aftermath...
The wheels then came off, and the fronts (i.e. new rears) went out for widening.
Back from widening...
Prior to mounting tires...
Man size; 325/30R19 Nitto INVO...
Mounted...
Then Chris Crawford (our GM technician) and I made a house call the morning after to install the new widened wheels on the vehicle. Now once again, prior to viewing these pictures, remember that I ordered the rear lug-incorporated spacers with about .50" more meat on the backside than we needed, just in case. I'd rather have too much material than not enough, and it turned out perfect, we just have to mill the additional material off to make the rear wheels fit perfect.
The lug-incorporated spacers going on...
Torquing down...
Setting in place...
The front spacer...
Front size...
Stock 285/35R19 on the left, new 325/30R19 on the right...
Sitting outside of his garage, wide stance...
Looks great, just needs to come in .50" or so...
Back at the shop, new front tires installed as well...
A half inch will make a world of difference...
Grrrr...
After inspecting, we decided we couldn't safely mill the spacers down (i.e. we'd take away a portion of the conical seat on the hub:spacer mating portion), so I ordered the same spacers, but designed for 20mm width instead and covered them for the customer due to my oversight...
With the increased offset with the new spacers we had to pin the fender liner back with a rivet...
Clearanced on the opposing side of the vehicle...
And wouldn't you know it, the one picture I took of the vehicle's new stance didn't save to my SD card. Figures.
Either way, this won't be the last we see of this car, so I'll take some pictures next time he's back in. We're currently awaiting our D3 Cadillac lowering springs to come in, and then those are going on next.
Stay tuned.
EDIT 05.19.10:
Two update pictures of the new sink/poke stance with the new rear spacers...
With stock ride height...
Lowered 1.00" rear/.75" front with D3 Cadillac lowering springs...
Update 06.06.10:
IMPORTANT INFORMATION IF YOU'RE CONSIDERING THIS MODIFICATION
We did run into an issue this week when the owner of the vehicle had three larger than average gentlemen in the back of the car, when he got on it contacting did occur. Unfortunately, it did damage the paint due to heat (not too bad, just right at the fender lip area, maybe 3mm visably affected), so we've taken the following corrective steps:
- Have fenders rolled and flared minimally (around 2-3mm at the lip)
- Mill spacers 4mm
- Clearance rear trailing control arm 2mm near lip of wheel
- Repaint damaged paint on rear quarter panels
- Replace damaged tires, we're potentially upgrading to 325/30R19 Michelin Sport Cup tires
To review, the best spacer size for the rear wheels is not 20mm, it's around 16-17mm to be safe. The fender rolling is NOT necessary and neither is the control arm clearancing, but the increased point-of-failure is worth our initial investment so we don't have to do this again.
Of course, all of this is on us, as it was my oversight that caused the damage. When it was just one person in the driver seat, one in the passenger seat it was fine. I'd venture to say that with average weight people in the back seat, the contacting wouldn't have occured. Either way, the customer's fine, he understands we're doing a bit of pioneering here, so these types of issues are accepted risks.
Like I always say; mistakes will happen, it's how those mistakes are addressed that defines an individual or business.
The plan I came up with after multiple measurement and theory appointments with the car on the rack:
- Move factory 19 x 9.5 wheels with 285/35R19 tires to front
- Supplement with 5.50mm spacer (this does not need to be hub-centric, as the hub-centric lip extends 11.50mm deep)
- Have factory front 19 x 9 wheels widened 2.00"
- Order custom lug-incorporated 31.75mm spacer (i.e. so this will bolt to the hub, then the wheel will bolt to this). I looked into having custom ARP lug studs made, but to hell if I was going to sell my customer $1,500 worth of lug studs. This was the most cost-effective route. Please note, I ordered these spacers with the intent of them being too large so we could mill them down to fit.
- Install 285/35R19 Nitto INVO on the front location
- Install 325/30R19 Nitto INVO on the rear location
And somewhere in between, burn the rubber off the stock rear tires.
The first test-fit spacer and tire came in for test fitting...
5.50mm front spacers fitting...
And lug-incorporated 31.75mm in the rear...
Fitting...
Fit perfect...
Now, to take care of these stock 285/35R19 tires in the most fun way possible...
Aftermath...
The wheels then came off, and the fronts (i.e. new rears) went out for widening.
Back from widening...
Prior to mounting tires...
Man size; 325/30R19 Nitto INVO...
Mounted...
Then Chris Crawford (our GM technician) and I made a house call the morning after to install the new widened wheels on the vehicle. Now once again, prior to viewing these pictures, remember that I ordered the rear lug-incorporated spacers with about .50" more meat on the backside than we needed, just in case. I'd rather have too much material than not enough, and it turned out perfect, we just have to mill the additional material off to make the rear wheels fit perfect.
The lug-incorporated spacers going on...
Torquing down...
Setting in place...
The front spacer...
Front size...
Stock 285/35R19 on the left, new 325/30R19 on the right...
Sitting outside of his garage, wide stance...
Looks great, just needs to come in .50" or so...
Back at the shop, new front tires installed as well...
A half inch will make a world of difference...
Grrrr...
After inspecting, we decided we couldn't safely mill the spacers down (i.e. we'd take away a portion of the conical seat on the hub:spacer mating portion), so I ordered the same spacers, but designed for 20mm width instead and covered them for the customer due to my oversight...
With the increased offset with the new spacers we had to pin the fender liner back with a rivet...
Clearanced on the opposing side of the vehicle...
And wouldn't you know it, the one picture I took of the vehicle's new stance didn't save to my SD card. Figures.
Either way, this won't be the last we see of this car, so I'll take some pictures next time he's back in. We're currently awaiting our D3 Cadillac lowering springs to come in, and then those are going on next.
Stay tuned.
EDIT 05.19.10:
Two update pictures of the new sink/poke stance with the new rear spacers...
With stock ride height...
Lowered 1.00" rear/.75" front with D3 Cadillac lowering springs...
Update 06.06.10:
IMPORTANT INFORMATION IF YOU'RE CONSIDERING THIS MODIFICATION
We did run into an issue this week when the owner of the vehicle had three larger than average gentlemen in the back of the car, when he got on it contacting did occur. Unfortunately, it did damage the paint due to heat (not too bad, just right at the fender lip area, maybe 3mm visably affected), so we've taken the following corrective steps:
- Have fenders rolled and flared minimally (around 2-3mm at the lip)
- Mill spacers 4mm
- Clearance rear trailing control arm 2mm near lip of wheel
- Repaint damaged paint on rear quarter panels
- Replace damaged tires, we're potentially upgrading to 325/30R19 Michelin Sport Cup tires
To review, the best spacer size for the rear wheels is not 20mm, it's around 16-17mm to be safe. The fender rolling is NOT necessary and neither is the control arm clearancing, but the increased point-of-failure is worth our initial investment so we don't have to do this again.
Of course, all of this is on us, as it was my oversight that caused the damage. When it was just one person in the driver seat, one in the passenger seat it was fine. I'd venture to say that with average weight people in the back seat, the contacting wouldn't have occured. Either way, the customer's fine, he understands we're doing a bit of pioneering here, so these types of issues are accepted risks.
Like I always say; mistakes will happen, it's how those mistakes are addressed that defines an individual or business.
Last edited by Jordan_NationalSpeed; 06-06-2010 at 09:10 PM.
05-12-2010, 04:22 PM
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Great write-up! BUT . .
after looking at those 'big meats' . .
i'm feelin' a little flacid.
Keep it up . . . with the great post. It's lookin' good and thanks.
PS ---- Hey, do I see rubber tire impregnated on the lower shock in that one picture.
after looking at those 'big meats' . .
i'm feelin' a little flacid.
Keep it up . . . with the great post. It's lookin' good and thanks.
PS ---- Hey, do I see rubber tire impregnated on the lower shock in that one picture.
05-12-2010, 05:56 PM
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Nice the inner fender liners are all you have to adjust to add 40mm more tire width? Or are you going to have to flare the insides of the wheelwell to prevent the fenders and quarters from impacting the tires over bumps?
the inner fender liners are all you have to adjust to add 40mm more tire width? Or are you going to have to flare the insides of the wheelwell to prevent the fenders and quarters from impacting the tires over bumps?
05-12-2010, 06:43 PM
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We widened the the wheels 2.00", and ultimately reduced offset from factory +51mm (remember, these are the front wheels we widened) to +31mm. This gives a PERFECT fitment with about a 1/4" poke out of the fender lip, it looks really mean.
So essentially, the new wheel values are as follows:
- Front
- 19" diameter
- 9.5" width
- +45.5mm offset
- Rear
- 19" diameter
- 11.0" width
- +31mm offset
That appears to be the perfect dimensions front to rear for optimum clearance. We'll see how it looks when we have the D3 Cadillac lowering springs installed, we're going to have a little bit of negative camber added in the rear to help tuck them with the 1.00" reduction in rear ride height.
I'll document the process and post the information on here, I'm sure the clearance will be retained.
05-13-2010, 12:08 PM
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Points to you, great write-up. Looks like you have a great solution to a problem that restricts many high HP cars. Your knowledge and commitment is great
Hopefully you will get a V1 in there and figure out how to go wider than a 295---there is a vendor on the other forum attempting to do this.
Hopefully you will get a V1 in there and figure out how to go wider than a 295---there is a vendor on the other forum attempting to do this.
05-13-2010, 05:31 PM
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Well I do appreciate the kind words, onebadcad.
The next V1 CTS-V in for work will hopefully be my next daily driver, I've just got to find the right car first.
The next V1 CTS-V in for work will hopefully be my next daily driver, I've just got to find the right car first.
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05-19-2010, 10:42 AM
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Kudos for all the pioneering you've done! Do you see any way possible that you can have the wheels and tires not sticking out so much? I'd love the extra rubber, but hate the look...
05-19-2010, 10:49 AM
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05-19-2010, 12:03 PM
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Here is an update picture of the poke/sink front-to-rear:
Last edited by Jordan_NationalSpeed; 05-19-2010 at 12:09 PM.
05-20-2010, 06:54 AM
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Watch Nick surprise us all and pull up in a murdered out '06 next week.
A few more pictures after the alignment (-1.3degrees front / -2.2degrees rear, tucks them in perfect)...
Rear passenger side...
Rear driver side...
The car has an amazing stance now.
A few more pictures after the alignment (-1.3degrees front / -2.2degrees rear, tucks them in perfect)...
Rear passenger side...
Rear driver side...
The car has an amazing stance now.
05-22-2010, 04:21 PM
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Not sure who Jordan used but I've widened my V1 rear wheels to 9.2" to fit some 275/40-18 tires. My inners were bent on 2 wheels so I fugured I'd have them widened. Check out www.EricVaughnMachine.com, Monrovia, CA. Eric did them for $300 each + shipping. Eric's number is 626-358-6413. Single weld with a new inner wheel blank - very professional job.
05-22-2010, 07:21 PM
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Not sure who Jordan used but I've widened my V1 rear wheels to 9.2" to fit some 275/40-18 tires. My inners were bent on 2 wheels so I fugured I'd have them widened. Check out www.EricVaughnMachine.com, Monrovia, CA. Eric did them for $300 each + shipping. Eric's number is 626-358-6413. Single weld with a new inner wheel blank - very professional job.
BTW, we had this V on display today at one of our dyno events, and it drew a lot of attention. Oh and I quite enjoyed running it on the rollers, we have a nice baseline, so now we can start making some power.
Very easy car to dyno, even with the A6.