2004-2007 Cadillac CTS-V General Discussion Discussion, 275's on factory rims (rear only) with pics in Cadillac CTS-V Series Forum - 2004 - 2007; I got GS-D3's put on. 245 up front and 275's in the rear. What little driving I've done feels fine. ...
I got GS-D3's put on. 245 up front and 275's in the rear. What little driving I've done feels fine. They hook up really well, which seems to have made wheel hop worse. It seems like they are really stretching the sidewalls in the back, so I'm guess they will wear badly. Here are some quick pics:
Front 245's left and rear 275's right.
This is a top down shot. I was actually a little further away with the 275's so in reality if I was the same distance the 275's would show more bulge
Unless things changed drastically I plan to stick with this setup. I love the look of it. I tooks some corners fast and hard, but at low speeds. Everything seemed good. They hook up really well, but it seems to make the wheel hop worse.
I'm talking about going around a 90 degree corner like turning from one city street to another at 30 mph. It's fast for taking that type of a turn, but ultimately 30 mph is slow. I haven't done any curves in the road at 60 mph.
dumb question....can you fit 245/275s on a base CTS with some 18x8in rims with out rubbing or rolling the fenders?
It is my understanding that the quarterpanels are the same between the models, so fenders shouldn't be an issue. I am not familiar with what control arms are used, and if they might cause a rubbing problem (for V's the rear is OK, but the front is an issue when going greater than 245-255).
The main issue that sticks out though, is your mention of an 8" rim, vs. the 8.5" inch used by the V. Putting 275's on an 8.5" is pushing it, I don't think putting 275's on an 8" rim would be a good idea. I'd think that putting 245's on an 8" rim would be similar to putting 275's on an 8.5" rim, it's beyond the recommended minimum size, but it shouldn't be a huge issue.
The V and the regular CTS have identical chassis. The main differences as it applies here are:
1) The stock V sits about 1/2" lower than a stock CTS. The tires are that much closer to the fenders.
2) The V wheels are 8.5" wide with 42mm offset. 275's have a recommended wheel width of 9" to 11". Wildwhl widened his stock V wheels almost an inch for proper fit. Clearly, the pics posted show they tires fit the stock 8.5" V wheels, with a little bulge at the sidewall. Installing on 8" wide wheels will increase that bulge by 1/4" on each side of the tire. I'm sure one could mount them to 8's but they would not be as tight a ride in corners as the sidewalls would laterally 'roll' on the rim with a side load. Not recommended.
3) Stock V has 42mm offset. I believe Wildwhl put ~5mm spacers to bring it to an effective offset of 37mm, to keep clearance from the trailing arm but not hit the inner fender. The popular 40mm should be fine for this, as the posted pic is with stock V wheels at 42mm offset.
Hmm, ok so how about an 18x8.5 with a 38mm offset, 245 in the front and 275 in the rear, does that sound like a winner? Iam still trying to learn about all this offset and stuff with the CTS and you V guys seem to be the only ones going bigger then 245. Also are you using 45 or 40?
To keep a consistent overall diameter, you should run 245/45 in front and 275/40 in back. That's what I've got, along with widened 9.25" stock wheels and 0.2" spacers (thanks, Wildwhl!) in the back.
I can feel more flexing with the GS-D3's in general, which you'd expect because of the difference in sidewall rigidity compared to the F1 Supercar EMTs. If you go with narrower wheels on a fat tire, the combination will yield even less rigidity. And mounting the tires to wheels that are narrower than recommended is a safety risk, up to and including losing bead seating while maneuvering - something that'll ruin your whole day.
In stock class autoxes, you will see people running 275 on 8" rims. Granted, this is with very stiff sidewall r-compound tires, but it is done with great success within the rules. It is not recommended to run 275 on 8" on the street, though. 255 is about the widest I'd run on an 8" for the street, without running insanely high tire pressures...
The Evo has 235s on an 8inch, STi has 225 on an 8"....many have run 255s with good results and not too much wag. In autoxes, the Evos mostly run 275...on a 17"x 8" rim, and they are almost unbeatable...almost.