different size tires - Page 2

pjbizjak · #16 (**permalink**) 11-04-09, 01:17 PM

I have an 07 STS 1SG with staggered tires and the rims are the same width on both front and back, just the tires are different size. So in this case you could put the smaller or larger size tires on all four rims.

STE_6000 · #17 (**permalink**) 11-04-09, 01:21 PM

Quote:

Originally Posted by pjbizjak

I have an 07 STS 1SG with staggered tires and the rims are the same width on both front and back, just the tires are different size. So in this case you could put the smaller or larger size tires on all four rims.

that doesnt sound right. staggered wheels are different widths for the wheels. you can put different tires sizes on the same 1 wheel, and usally you have different side walls,but staggered wheels means the wheels are the same for the front but different to the ones in the back. did you measure all 4 wheel widths to make sure they didnt put ur bigger wheels on one side, or that u even where given staggered wheels.

next2pool · #18 (**permalink**) 11-04-09, 01:34 PM

I agree--something doesn't sound right. On staggered 17" cars, the front should be 7.5 and the rear 8.0. Now there does seem to be some difference in marking or identifying the wheels. Some will have the width specified on the inboard side of the hub, while others will say "rear only" You may want to check your oprion codes to see if it originally came with staggered tires.

JGarten · #19 (**permalink**) 11-04-09, 11:04 PM

Quote:

Originally Posted by next2pool

I agree--something doesn't sound right. On staggered 17" cars, the front should be 7.5 and the rear 8.0. Now there does seem to be some difference in marking or identifying the wheels. Some will have the width specified on the inboard side of the hub, while others will say "rear only" You may want to check your oprion codes to see if it originally came with staggered tires.

Yah, remove the center cap and you'll find [REAR ONLY] stamped on the wider rims and [GM] stamped in the same place on the narrower rims. That's how I figured out that both [REAR ONLY] rims were on the right side and that's how I confirmed the stealership moved them to the rear.

The tread circumference of the tire is fixed no matter how far you deflect the sidewall (within reason, steel belts don't stretch, eventually you'll deform the round tire into an oval). Deflecting the the 235s and extra quarter inch is virtually irrelevant. I would be surprised if anyone on this forum, especially myself, could tell the difference (unless maybe you've got a super-charged V or you're just insane). How much do you think the sidewall deflects under heavy lateral loads anyway? More than a quarter inch! If any tire were to break the bead under any lateral loads we can put on them (short of physical contact with an obstacle) before the tire loses traction, we're all in big trouble! These aren't racing slicks, they're passenger car tires. Yes 255s will give you more lateral grip, but will you really use it? When you panic snap turn the wheel, will 255s (even w/stability control) keep you from spinning out? I can only speak from my experience with 235s on staggered rims, and I vote "Yea".

mrchipster · #20 (**permalink**) 11-05-09, 06:26 PM

I was going through the same thing when I was trying to find snow tires for my 05 RWD STS. I have the staggered setup (235/50/17 front and 255/45/17 back). I called Cadillac headquarters and it was confirmed by my local dealer that you can (and they recommend) that you run the 235/50's all around. I bought some Blizzak LM-22's for the winter and will put the Michelins back on in the summer. My rims are also 7.5in. front and 8in back. They do have the 'rear only' stamp on the larger (8in) rims . The 235's fit fine and work well so far. Once the snow flies I'll know how good they really are but I expect them to perform well. I'll probably only run the 235's all around for the winter and go back to the original staggered config. all other times since this is how it was designed.

EChas3 · #21 (**permalink**) 11-07-09, 12:17 AM

Quote:

Originally Posted by STE_6000

that doesnt sound right. staggered wheels are different widths for the wheels. you can put different tires sizes on the same 1 wheel, and usally you have different side walls,but staggered wheels means the wheels are the same for the front but different to the ones in the back. did you measure all 4 wheel widths to make sure they didnt put ur bigger wheels on one side, or that u even where given staggered wheels.

I know my 2006 1SG has staggered tires on identical 18" rims. The circumfrance of the two sizes of tires are very close.

I think the 2007 1SG is the same.

STE_6000 · #22 (**permalink**) 11-08-09, 08:15 PM

Quote:

Originally Posted by EChas3

I know my 2006 1SG has staggered tires on identical 18" rims. The circumfrance of the two sizes of tires are very close.

I think the 2007 1SG is the same.

that still doesnt sound right. i'd just randomly quick cadillac about that and see if they agree to that statement. and if they dont then u can say hey, why does mine like that. staggered wheels are different thickness.

EChas3 · #23 (**permalink**) 11-08-09, 10:32 PM

It is what it is.

STE_6000 · #24 (**permalink**) 11-08-09, 11:47 PM

doesnt make sense for cadillac to charge so much money and keep same width wheels but charge u half a grand more for different size rear tires. but in the end for this its gonna be what ever the person wants to buy and what ever recommendations the pro says. i just know what i'd be doing.

Greg00coupe · #25 (**permalink**) 11-11-09, 01:52 PM

Well this was the thread that made me curious enough to investigate. I have an 05 with the 1sg 18" wheels.

I pulled the center caps, nothing stamped on there. Surely if I jack it up and pull off the wheels there will be some dimensions stamped on the back side of a spoke???? Nope lots of numbers but they were all identical between the rear and front wheels. I did confirm the wheel sizes for all 4 wheels by careful measurement.

What concerns me is if you go to get new tires how can you be certain the tire store gets the right rim and tire combo?? You have to be a very proactive consumer for something like that. Heck last time I had tires put on the 00 STS they left the lug caps loose and I found them all over the street!!!

Onalaska · #26 (**permalink**) 11-12-09, 09:39 AM

I had 17" staggered tires. I split the difference, put P245-45-17's all the way around which is a very common size. Slightly different diameter than stock, but made very little difference in speedometer reading. Still going after over 20,000 miles and I rotate them regularly.

SlickCityStan · #27 (**permalink**) 11-12-09, 10:12 AM

after all is said and done I think whoever [at cadillac] came up with the idea of wider tires on the rear did so for marketing. Wider tires on the rear have two reasons for being there 1. More rubber on the ground for better traction,2 softer ride. There are too many STS's with same size tires all around that have not had any negative effects on ride, handling, or any kind of suspension problems. If any have

had any such problems, speak now or forever hold your peace!

MacMuse · #28 (**permalink**) 11-12-09, 03:58 PM

Quote:

Originally Posted by SlickCityStan

... If any have

had any such problems, speak now or forever hold your peace!

Sounds reasonable in theory, but I don't have the CASH to swap between staggered and non-staggered just to see how it handles on the same car. Mine came with 4x235/50R17, and when I got the car at 30K miles it handled like driving on ice skates after a deep freeze anytime the road was moist.

I admit I'm curious about differences in real world handling between staggered and non, but for now I'm happy and not sliding all over the road with my Blizzak LM22s on all 4 corners.