I noticed that there is a chunk out of the sidewall on my right front tire. Question is, with 19000 miles on the original Michelins, can I replace just 1 tire or do I need to match them due to wear because it's all wheel drive and the new tire will be slightly larger than the worn ones? I have the 19" wheels so they will run me close to 300 installed each. My other option (if I have to replace multiple tires) is to buy aftermarket 17" wheels & 17 inch tires which will save me in the long run when I have to buy new tires down the road.

 

I did find that you should have no more than 2/32 of an inch difference between tires.
Next Question, If I do change from 19" to 17" wheels, is there anything else that needs to be done like anything need to be programmed into the PCM or TCM. Thje outer diameter should be the same since this car came with both sizes, either 235/65-17 or 235/55-19, so I would assume it should be an even swap.

 

I am by no means an expert but my personal opinion is that your noted maximum difference of the tires shouldn't exceed 2/32 is extreme ..........

Unsure if that is tread depth or that is the diameter of the tires.........

2/32 = 1/16 = .060 = Equals the thickness of a penny.

Does common sense prevent me from believing this amount of difference would ever be an issue ?........ Yeah it does.

I personally would not hesitate to put another tire onto the vehicle and if I was in your position and money was tight I would probably look for a used tire to match up tread depth within 1/8" to 3/16" of the other three.

I just don't comprehend how it could hurt.

 

Just an additional thought........ a new tire has .312 (5/16") of tread depth. A tire with 19K miles on it may be about half worn or with approx. .156 (5/32") tread left.

That makes a 5/32 difference in the radius of the new versus existing. I'd put a new one on without a second thought.

 

Stick a new tire on it and call it a day. The issue you are referring to is mainly a concern on AWD cars/trucks where the front axle and rear axle's combined "power ratio"(i.e. 50/50, 60/40) is closer together. These systems are usually highly advanced because driveline wear and fuel economy will suffer due to an imbalance of power. The minimal tire wear on your original tires compared with the new tire will be overshadowed by the "traction assist AWD" system in the Pacifica. This is in no way an inferior system, but a different design and purpose.

 

Thanks for the input guys.
I called the dealer on Saturday & asked since if it screws up the drivetrain they're the ones that have to fix it under the 3/36 warranty and my extended warranty (if chryslers bankrupt status doesn't negate those warranties???) and the service manager said not to worry unless the original tires were down to 2/32's which would mean I needed new tires anyways. I got the one new tire which, as stated above by SARG, is 10/32 new and my old tires with 20000 miles (just turned over 20000 saturday) on them were 7.5/32's so less than 3/32's difference isn't that bad. Now that it's done I do plan to shop around for OEM 17" wheels and will go from my present 235/55R19 to 235/65R17. Reason is that the 19's cost over 250 each AND aren't readily available (only 4 options for that tire versus about 40 options for the 17's & they only cost about 120 for most of them). Nobody had them in my area, all were special order so I had to drive to NTB in wilmington Del to get that one replaced. I live in Deptford NJ (hence the name "indept") so it was a little bit of a drive. What happens if we go on a cross country trip & need a tire, I guess I'd be spending a few days in a flea infested hotel while the tire was special ordered.