Tire circumference conundrum

[cperez]

Here's my story which may be more of a thought exercise:

I recently had a slow leak in one of my rear OEM Continentals. Upon inspection, my trusted indie LR shop noted that it was a failing internal patch from a previous puncture (I bought this MY'11 as a pre-owned vehicle). They were reluctant to re-patch it for safety/liability reasons and I concurred.

The OEM tires had about 40-50% life remaining so I wasn't crazy about replacing all of them because of this single leaker. It wasn't a huge budget issue but just seemed wasteful to me. The shop agreed that it would make sense to only buy one new pair, which I did and which they mounted/balanced/aligned for me. Incidentally I purchased two Bridgestone Dueler H/L Alenza Plus as the new pair, obviously in the same size as the OEM Contis.

A few weeks later I was in the dealership for a few warranty items. The service consultant noted the two Bridgestones and asked about them. I explained the history above. He said that I should consider a fully matched set of tires with similar wear cycles because even a few 32's of an inch in diameter difference could cause issues in the front and rear differentials. On paper his theory made sense to me but I had to wonder if it mattered in the real world. Another tech I spoke with upon pickup seemed to agree with me.

Today while perusing the forum I saw a bumped thread about tire pressures which referenced LR's own specifications calling for higher PSI in the rear. This brought my situation to mind-- wouldn't different front/rear PSIs also create different tire circumferences? (albeit small but measurable). If so does this make the dealership tech's point moot?

I'd be interested in your thoughts. In practical terms is this something that would concern you?--

a) Having 2 brands of properly sized tires installed (aesthetics aside)
b) Having minimally different circumferences between front and rear tires (either due to wear or PSI)

Chris

 

[ivan gonzalez]

I have never been told that having to sets of differently worn tires can damage anything except uneven ware on the tires. Hell I got my truck lifted 2 inches in the front to even it out since all pickups usually are higher at the tail and have had no issue with it in the 5+ years its been

 

[umbertob]

As long as the set on the same axle is an even match and the difference between front and rear axles is minimal, you will be alright. Having more than a nominally different circumference between the two front wheels can create problems though, not so much with the differential but with the transmission. If you have an odd-sized tire (it can happen if you have four well worn "running" tires and you find yourself needing to replace a flat with a brand spanking new spare...), put that wheel on the rear axle if possible.

 

[cperez]

Thanks for the input which is reassuring. Both new tires were installed on the front (yes I'm aware of some conventional wisdom stating that new tires should go on the rear but my decision process on that is fodder for another thread)...

My slight OCD tendencies will probably kick in soon and the thought of running on 2 diff brands of tires with different wear patterns will become unbearable. But for now I'm OK with it!

 

[Surfrider77]

Do you rotate all 4 tires though? I do a 5 tire rotation (includes spare) and by the time a full rotation has completed, a single tire would have seen every corner of the vehicle + underneath as spare duty. This 2 + 2 configuration would potentially have those tires mismatched at some point.

Not sure about the contis, but my Nittos are non-directional.

More onto your original point, the front and rear differences are completely trivial. The center diff is open the vast majority of the time anyway.

 

[cperez]

Definitely planning to rotate the tires but don't have full size spare on my HSE unfortunately...

 

[Disco Mike]

First run all your tires at the same air pressure, different tire pressures will cause the lower air pressured tires to grab better the the higher pressured tire which which with time especially with your traction control to show wear, especially on your brake pads.
Never run 2 different tread designed tires when two of them are so warn.
Last lee, only do a 4 way rotation leaving your full size tre alone then when you need new tires, just buy 3 matching tire, same as your spare.

 

[cperez]

Never run 2 different tread designed tires when two of them are so warn.

So Disco Mike, you're not loving the idea of the Bridgestones paired with 40% Continentals? Duly noted.

As mentioned, I'm less concerned (from a practical standpoint) about my setup after reading the great input and reasoning here. At this point my remaining motivation to get 2 new B'stones is simply to satisfy my neurosis.