: Tire size difference on N* SRX



King3244
01-22-07, 07:00 PM
I was looking for tires the other day on Tire Rack and noticed that although the front and rear tires on my 2004 SRX are different sizes that they have the same diameter.

Has anyone put the larger size on the front? I can't imagine any clearance problems but you never know.

This would sure help for tire rotations, being able to rotate the fronts to the back and vice versa rather than just side to side.

My wife just drove the SRX for the first time today and I guess I am not going to be getting my STS 4 anytime soon......she loves it.

Northern SRX
01-22-07, 09:07 PM
I imagine that they'd fit as I believe that the wheels are all identical specs (18" x 8" with 51mm offset) but keep in mind that the car was engineered for a slightly narrower tire up front for the 18" wheel set up. The narrower (but still ample) contact patch up front helps by providing somewhat easier steering and puts the beefier tire where you want it - for maximum traction out back. Plus, the beefier tire out back helps handle the anticipated additional cargo/passenger load.

It all depends on what kind of ride you're trying to achieve and your tolerance for additional strain on your front suspension/steering components. I personally won't change the widths on mine just to permit tire rotation but I cannot see any ride advantage to putting wider tires up front. However, a reasonable solution might be to also put the narrower tires out back but then you'd be losing some rear traction - again, it all comes down to how much you value that additional road adhesion. Still, the best solution is to just grin and bear with the factory set-up - IMHO.

Also, forgot to add that Cadillac recommends against rotating the 18 tires from one side to the other.

FarEast
01-23-07, 10:34 AM
Check this tread out...

http://www.cadillacforums.com/forums/cadillac-srx-forum/94232-fyi-goodyear-tires.html

King3244
01-23-07, 07:59 PM
So if you can't rotate side to side then there is no rotation at all......not good with a 4 wheel drive vehicle.

As to OEM tires..... that is what they are...... a special tire built to the auto makers specs. The tires you get at Walmart and Costco etc are again built especially for discount tire places. The wear on OEM tires has been bad since they started making tires but that doesn't mean that your replacement tire is going to wear or act the same.

I am an old fashion guy and I am going to go to the rear tire size all around so that I can rotate them.

King

Smokin' SRX
01-25-07, 04:19 PM
I was looking for tires the other day on Tire Rack and noticed that although the front and rear tires on my 2004 SRX are different sizes that they have the same diameter.

Has anyone put the larger size on the front? I can't imagine any clearance problems but you never know.

This would sure help for tire rotations, being able to rotate the fronts to the back and vice versa rather than just side to side.

My wife just drove the SRX for the first time today and I guess I am not going to be getting my STS 4 anytime soon......she loves it.


Hey King3244, love your taste in autos! I have posted, as so many others on this site have, that it's do-able!

Just did mine 3-4 months ago. Went to larger rear size, all around. Drives, handles and feels great! Mavis.com ships and installs also, at their own national (USA) shops. I got Dunlap Sport 5000 Symmetrical (in "H" speed rating as opposed to OEM "V" rating)

They're good for 130 MPH :D . At $169 each, you can keep the Michelins...........and now I ROTATE!

Northern SRX
01-26-07, 06:42 AM
I wonder if Cadillac might refuse warranty service on front suspension parts if they deem the tire to be too wide.

Funny, I did think about going same width all around but I would have been more tempted to go to the narrower width for winter driving and the wider for the summer set. At the end of the day, I kept both sets of tires at the original specs.

donjumpsuit
01-26-07, 01:22 PM
I wonder if Cadillac might refuse warranty service on front suspension parts if they deem the tire to be too wide.

Funny, I did think about going same width all around but I would have been more tempted to go to the narrower width for winter driving and the wider for the summer set. At the end of the day, I kept both sets of tires at the original specs.


Ok,
Here we go. I have had my 20"s on since mile 5000k, I have started to have problems with my engine at mile 20000k. GM's engineerers and everyone has been working on my car for the past week, taking it all apart , blaming it on a pinched wire, or a bunch of different parts they are now replacing. During this process the informed me (which I knew) that there are two different size tires on the car, and that I need to have a "talk" with the lead mechanic on my car about how using aftermarket tires of the same size will cause differential problems in the future, which will NOT be covered by the warranty.

NOW, when I got the car, I was told I could put on any rims I wanted, told by the salesman SELLING me the car. Because I wanted different rims because the stock rims on a 60k car are utter garbage. At the time there were no sport 20's offered by caddy, like there is now. SO, who's right and who's wrong.

FarEast
01-26-07, 01:42 PM
From what I've been reading and hearing even thread wear is very important for a 4 wheel drive vehicle. Achieving even thread wear means regular tire rotations. What happens if you don't rotate tires regularly which you forced to do in the case of SRX? Differences in thread wear as small as 3/16 of an inch between axels put a strain on differentials which could lead to a.... drumroll... premature drivetrain failure. So... go figure what's gonna be worth for the vehicle: bald fronts and shiny new backs OR wider fronts and even wear on all four?

King3244
01-26-07, 02:32 PM
What I want to know is why in heck did they put different sized tires on the vehicle in the first place???

The diameters are the same due to the different aspect ratio so they didn't gain or lose anything there. The have to be on the awd obviously or they would have all sorts of problems.

Things that make you go hmmmmmmm!

TSS
01-26-07, 03:21 PM
This is not the first car I have had with OEM staggered tires, although it is the first with AWD.

It is ridiculous IMO - even if there are some negligible advantages.

jigou
01-29-07, 04:58 PM
I'm pretty sure (as in 99% sure) that the 2007 Sport package SRX I saw at a local dealer a couple of weeks ago had the same size tires on all 4 corners (255s).

I did NOT verify that it was AWD vs RWD.

ttaebel
02-02-07, 04:40 PM
Hi,
I am also considering going to the 255/55-18 all around. I called Tire Rack and the representative said that I would have clearance problem on the front tires. Is this so? and did you have to use any spacers on the front and what re alignment.
Tks TCT









Hey King3244, love your taste in autos! I have posted, as so many others on this site have, that it's do-able!

Just did mine 3-4 months ago. Went to larger rear size, all around. Drives, handles and feels great! Mavis.com ships and installs also, at their own national (USA) shops. I got Dunlap Sport 5000 Symmetrical (in "H" speed rating as opposed to OEM "V" rating)

They're good for 130 MPH :D . At $169 each, you can keep the Michelins...........and now I ROTATE!

Kauai 1
02-03-07, 11:46 AM
I put 255/55-18's on all 4 wheels.......V-rated snow tires. No clearance problems. I have noticed new SRXes on Cad dealer's showroom floor with after-market 22 inch wheels with same size big, wide tires on all four locations.

FarEast
02-03-07, 12:07 PM
Hi,
I am also considering going to the 255/55-18 all around. I called Tire Rack and the representative said that I would have clearance problem on the front tires. Is this so? and did you have to use any spacers on the front and what re alignment.
Tks TCT

They are overly cautious. No clearance issues with my 255/55-18 GoodYear Eagle Response Edges whatsoever.

jigou
02-05-07, 10:22 AM
A little more food for thought:

Front tire: 235/60/18 = 91.4 inches in circumference, 693 revs per mile
Rear tire: 255/55/18 = 91.2 inches in circumference, 694 revs per mile

Not enough difference to worry about, and barely enough difference to measure.

Jarrod

Smokin' SRX
02-14-07, 01:17 PM
What I want to know is why in heck did they put different sized tires on the vehicle in the first place???

The diameters are the same due to the different aspect ratio so they didn't gain or lose anything there. The have to be on the awd obviously or they would have all sorts of problems.

Things that make you go hmmmmmmm!


I have the 4 same size as I stated above w/ no problems. (went wider, rear, oe size at all compass points).

Seems they did this because the calibration of the stability control is set to work with a narrower front tire, in order to NOT spin the tail end around on a fast steering wheel turn! Naturally, A wider (i.e.......same as the rear)front tire would give more frontal grip on the road and make spin arounds easier! Don't forget, all the Auto magazines test these new vehicles to the limit!! Maybe Caddy didn't want their new "baby" to get a bad ("... loses control easily under extremes...") write up!?
Anyway, no problems with mine at 4,000 miles!:bouncy: