Replaced all four of my tires at DT today. Wasn't sure at first if the guy was just trying to sell me new tires, but I went for it ($500 with replacement coverage). I feel better after reading this thread.

I broke 30k miles earlier this month and ran over a nail yesterday. He said my other tires were just as worn as the damaged one, and they'd last maybe another month. Suggested that I rotate every 5-6k miles to extend the life of the tires, but I was getting them done only when I got the oil changed (10k). The replacements are Yokohama YK520. Since I can get them rotated and balanced at no additional charge, I'll plan to do that at least every 5k miles...

 

Most of the difference is simply due to tires with a little vs. a lot of tread. The deeper tread on the new tires adds rolling resistance because the tread blocks squirm slightly as the tire rolls across the pavement. A worn-out tire has less squirm (and traction). As these tires wear out your mileage will slowly improve again, all other factors remaining constant.

 

Thought I'd share a follow-up. After a series of 56+ mpg tanks (37 psi), my post-new tire mileage dropped over 3 mpg on the last tank (driving conditions mostly unchanged). According to the DT invoice, the four new tires were filled to 32 psi. The ride seemed off (some sideways drift when going over 50 miles per hour?), and I was having trouble getting the metered average even close to 52 mpg. After filling up yesterday, I finally checked my tire pressure. Two tires were filled to 32, while the others were at 36:

36--32
---X---
32--36

HUH! I increased pressure on both 32s to 36, and so far the metered average is looking better (52+, but it's still early in this tank).

 

Anyone considered the effect of the major negative camber on the rear end of the HCH II which might be causing these tires to wear faster? Have a look lengthwise on the latest civic (almost all models) I am not sure why they put so much negative camber on the rear, but when I noticed it the first thing that struck me was "I wonder how much that accelerates tire wear?"

Might be worth doing some adjustment and dialling some of it out.

 

I've noticed this too. I can only hope it help lateral movement in the rear. They are def tuned that way on purpose. I would second guess Honda, but I would definately rotate often!

 

Regarding the Michelin Harmony tires, I believe they have a very long life span, i.e 80K miles or so.

80K miles for a set of tires is quite a lot and may offset the slightly lower mpg you are getting (4.5% esimated).

 

I am going to need a couple of tires soon for my HCH II, I have spent some time tonight looking at choices at tirerack, I would get another set of OEM bridgestones but they are on back order, so I reckon I might go for the michelin harmony's. Interesting, I couldn't find the destiny tires on their website.

I'll report back on my gas mileage findings with some new tires on.

 

That's because the Destiny is a model made specifically for Discount Tire. They claim it's a relabeled Harmony.

 

http://www.tirerack.com/tires/Spec.j...tirePageLocQty=

Note that the Harmony weighs 21 pounds. If you check the OEM tires, they weigh 18 lbs. That little bit of extra rotational mass could have an impact - but I'm not an engineer so wouldn't swear to it...

v/r

mcj