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Originally Posted by spacemanspif
It's looking like I'm going to need tires soon as my right rear tire is wearing faster than the left. Guessing an alignment is in order as well and since I replace tires in pairs I'll be buying 2 new tires and have a few questions on types and size.
1. I am currently running 195-60-15 and am thinking about getting narrower ones; 175-65-15 are 0.2" shorter than the 195-60s. Wondering if 175s on a 6" wide wheel are too narrow and/or MPG beneficial? I'd like to consider safety as well, I don't drive like a crazy person but I want to be safe in all weather conditions and will take a small MPG hit to retain safety........
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That is going the wrong direction for safety. That is going down in load carrying capacity and directionally that is towards increased risk of tire failure.
Also, not only is the vehicle being required to operate at a higher rpm for a given speed - which usually hurts fuel economy - but the rolling resistance is actually worse for a smaller size (all other things being equal).
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Originally Posted by spacemanspif
2. LRR tires in both sizes seem to start around $80/each on tirerack.com and there are tires $20 less that aren't. Will LRR tires pay for themselves in savings? What are some realistic gains to be had from these tires? .....
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I think this depends on how much highway driving you do compared to how much city driving you do.
Tires with low rolling resistance tend to wear more rapidly, and city driving causes tire to wear more rapid, so the combination might result in more money being spent to replace the tires more often.
But be aware that the term "LRR" is a relative term. It means "Better RR compared to other tires with similar wear and traction properties" - and with that in might, it would be better to have LRR than not. You need to decide what compromise you are willling to live with.
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Originally Posted by spacemanspif
.........For reference, with my taller geared trans I cruise at 2,000rpm @ 60mph. I think that it is about at the bottom of my eco range and think that spinning the engine a little more might be beneficial for my 95% highway commute. Thinking that a little more rpm might keep the engine from loading so much while climbing all the overpasses I deal with and might net a small mpg gain, or at least not take a hit (hopefully).
Thanks,
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Based on that you will get many miles out of a set of tires - and you would benefit from a larger diameter tire.
Try to fit as large a diameter tire as you can - best guess not knowing your exact vehicle is 2 sizes larger. (Even if you tell us the exact vehicle, we won't be able to tell what fits as there aren't any charts published that tell us how big the fenderwells are.)
The second part is careful tire selection. Unfortunately, RR values aren't published as there are a number of RR tests and they don't give the same value. To compare tires, the tests have to be the same.