CT5-V Max tire size (diameter, width) you can put on stock 5BW suspension w/no rubbing?

[No Usury]

These cars have been out for a while, but I don't see many (if any) posts outlining folks who have tried increasing tire width and/or diameter, together with their associated results.

I know Cadillac engineers got pretty close to maxing out tire under the wheel well, but how close, exactly... anyone know?

 

[MatthewAMEL]

For the Precision Package, GM has been able to fit a 285/35-19 in the front. That's 100% due to a revised front knuckle that allows greater negative camber. (-2.8) They stayed at 305 in the rear.

Anything above 315 and I would start looking at the tire width specs. Some 315's are narrow and some 315's are wide. Some 325's are closer to 305s.

 

[FLYARMY]

The turning radius already sucks on these cars !

 

[A Blackwing]

The turning radius already sucks on these cars !

yup. exactly why for best results a quick clutch kick spins the car around much easier then a 3 point turn.

 

[FLYARMY]

What's a "clutch" ? LOL !

 

[coffee_time]

For the Precision Package, GM has been able to fit a 285/35-19 in the front. That's 100% due to a revised front knuckle that allows greater negative camber. (-2.8) They stayed at 305 in the rear.

Anything above 315 and I would start looking at the tire width specs. Some 315's are narrow and some 315's are wide. Some 325's are closer to 305s.

I'm hoping that a pair of 315 PS4S (or 5S) when I need to replace the rears fit with no mods. But you are 100% correct, not all tire widths are the same even if they fall into the same obvious spec.

 

[MDM]

Any proven combo for drag radials on the stock wheels? The car definitely needs all the help it can get in first gear.

 

[No Usury]

Any proven combo for drag radials on the stock wheels? The car definitely needs all the help it can get in first gear.

Actually, if you want drag radials, I'd say 18" wheels & tires are the way to go.

Given that, I'm curious if anyone's found 18s that fit over our brakes.

Anyone know if the CCBs are the same diameter, etc. as the stock brakes?

 

[sonny200]

Post in thread 'Absolute Dearth of All-Season Tires for CT5-V Blackwing'

Dec 19, 2024

From the Michelin website:

MICHELIN Pilot Sport A/S 4 325/30 ZR19 101(Y) ZP BSW​

MICHELIN Pilot Sport A/S 4 275/35 ZR19/XL 100Y​

I got their RF version on the rears because that's all they had at the time I needed new tires. I haven't had an issue with them. They are great in the rain as compared to the OEM Pilot 4S.

• sonny200

I had to add 6mm spacers on the rears to avoid rubbing the inside wheel well liner.

 

[PrimeTime]

Post in thread 'Absolute Dearth of All-Season Tires for CT5-V Blackwing'

Dec 19, 2024

From the Michelin website:

MICHELIN Pilot Sport A/S 4 325/30 ZR19 101(Y) ZP BSW​

MICHELIN Pilot Sport A/S 4 275/35 ZR19/XL 100Y​

I got their RF version on the rears because that's all they had at the time I needed new tires. I haven't had an issue with them. They are great in the rain as compared to the OEM Pilot 4S.

• sonny200

I had to add 6mm spacers on the rears to avoid rubbing the inside wheel well liner.

With 19"?

 

[PrimeTime]

Just went 315/30ZR20 and 295/30ZR20 PS4's for a driver and the look and I'm expecting ZERO issues (Rubbing, tucked and no poke.... or anything else).

Tech Bronze specs on the shelf with new PS4's rears waiting.

Installing with lowering springs....Miles and F!@#$% SMILES! Driveability or I change her back.

325's is what it is a full 12" tire. Meats!

 

[clm5980]

Here you go. 20s in the front 18s in the rear with MT.

 

[sonny200]

With 19"?

Yes. With the 325 on the 19, it would rub on the inside. The 6mm spacer brought it out enough so it would not.

 

[flipray]

These are 20x10.5 +13 20x12 +50 285/30-20 and 335/25-20 Continental Extreme Contacts2.

 

[Champale]

These are 20x10.5 +13 20x12 +50 285/30-20 and 335/25-20 Continental Extreme Contacts2. View attachment 28833

flipray has just won the thread!! Wow that's superb!

 

[Champale]

These are 20x10.5 +13 20x12 +50 285/30-20 and 335/25-20 Continental Extreme Contacts2. View attachment 28833

Are you able to share alignment specs? I saw you mentioned slight rub up front - do you think at stock ride height and with more camber that issue would go away?

 

[PrimeTime]

It's tucked super tight on the nose @Champale ..... I'm with you on the info share request to @flipray if he is willing to share. Thank you!

I'm trying a 295/20 in the front with springs. Soon.

 

[Champale]

I've done a ton of wheels with custom offsets over the years and have some PTSD from wheels that didn't fit as promised by the wheel manufacturers. Very well known brands. If flipray has found the secret sauce, I might pull the trigger. Those huge rear tires are essentially the same OD as the OE 305s (the 335s are a fraction of an inch taller), which is perfect.

I really need to put my car on my lift and take some measurements one of these days.

 

[No Usury]

These are 20x10.5 +13 20x12 +50 285/30-20 and 335/25-20 Continental Extreme Contacts2.

Those huge rear tires are essentially the same OD as the OE 305s (the 335s are a fraction of an inch taller), which is perfect.

I really need to put my car on my lift and take some measurements one of these days.

PS4 325s actually have more tread than the Continental 335s (12.2" vs. 11.8").

 

[flipray]

Are you able to share alignment specs? I saw you mentioned slight rub up front - do you think at stock ride height and with more camber that issue would go away?

I gotta find my sheet but definitely something that can be fixed with more camber. The upper perch hole on the car is slotted and thats how you adjust camber. When I did my springs, with the anticipation of the wheels, I pushed the upper as much as I could to get more distance between the top of the wheel and the strut. Its unneeded once I saw how much more space I got once the wheels were mounted.

It's tucked super tight on the nose @Champale ..... I'm with you on the info share request to @flipray if he is willing to share. Thank you!

I'm trying a 295/20 in the front with springs. Soon.

Its supertucked just because the picture was taken during a turn. Its not that bad really.

PS4 325s actually have more tread than the Continental 335s (12.2" vs. 11.8").

This, I went with the ECS2 with that in mind since I wasnt 100% of space. Seeing how much space I got, I'll probably go back to 325 PS4s when Im done with these ECS2s. I think im getting there with atleast 15K miles on them by now.