Low rolling (eco) tyres VS overinflation

[topcat]

What are the relative gains of low rolling resistance (LRR) tyres versus over-inflation of standard tyres?

i.e. is it really worth the extra cost of LRR tyres, or will high PSI in standard tyres do the same thing?

The thing is, my usual Uniroyal Rainsport 2 tyres are great in every other respect (especially wet stopping) but they are only average on rolling resistance. If I pump them up hard, does that make them as good at rolling as LRR tyres???

It looks like LRR tyres are lacking in other (important) areas (like grip!), as always there are many trade-offs going on.

[Daox]

I dunno about over by you, but the LRR choices here don't really cost anymore than other tires.

To answer your question though, yes its still important. I don't have a link handy, but it was a TireRack article that said that 2/3rds of the rolling resistance of a tire come from the tread itself (design and material) where 1/3rd comes from sidewall flexing (which air pressure helps negate). So, buying LRR tires is still quite important.

[Piwoslaw]

Imagine where overinflating LRR tires would get you...

[gone-kl]

On a related note, is it more dangerous over-inflating LRR tires than sporty or all weather tires? Will it cause more blowouts?

I agree LRR tires aren't more expensive. I think the reduced grip can be compensated for with reduced speed, thus negating any negative effects from unforeseen road events. In other words, don't buy LRR tires for road raging.

[deathtrain]

dont road rage for MPG

[euromodder]

Originally Posted by topcat

What are the relative gains of low rolling resistance (LRR) tyres versus over-inflation of standard tyres?

I got about 7% out of the Michelin Energy Savers.
I already ran my previous tyres at somewhat higher than placard-pressure and continued that with the Energy Savers.

At 7%, given their long lifetime, and despite the elevated Michelin prices, it's still a good deal over time.

If you want to get them for their fuel efficiency, get the tyres that are best at reduced RR.
Not all tyres labeled as LRR actually are.
Check out the tests by ADAC and the like.

For saving fuel, in 2009/2010 the best were the Energy Saver and the Goodyear Efficientgrip - the newer stuff might do better, but no guarantees.

i.e. is it really worth the extra cost of LRR tyres,

Depends on your goal.
If you want to go for cheaper tyres , the lower price of the normal tyre may offset the gain in fuel economy. You'd have to compromise on endurance or grip as well .

At 7% less fuel and long endurance, LRR fit the bill for me.

or will high PSI in standard tyres do the same thing?

Partly.
But higher inflation on a LRR tyre will improve the fuel economy as well.

I can't single out the effect of higher pressure on my fuel use as too much has changed simultaneously.

The thing is, my usual Uniroyal Rainsport 2 tyres are great in every other respect (especially wet stopping) but they are only average on rolling resistance. If I pump them up hard, does that make them as good at rolling as LRR tyres???

Not likely to happen.

It looks like LRR tyres are lacking in other (important) areas (like grip!), as always there are many trade-offs going on.

I've usually been running better, sportier stuff than the Uniroyals.
(think Michelin Pilot series, Conti sportcontact 3, ...)

Going to the Energy Savers was quite a leap of faith, but they've held up well. (Mine are W rated though, yet I only need T.)


If you change your mindset and driving style, good LRR tyres will certainly do, despite their shortcomings / different compromises.
Compared to a sporty tyre, you do lose grip and braking performance, so you should be prepared to compensate for that in your driving.

It's all part of changing the nut behind the wheel

[toc]

Originally Posted by euromodder

It's all part of changing the nut behind the wheel

I'm still trying to find the right spanner for that nut.

Here in Aus, I'm trying to find which LRR are the best. So far I've only come up with Michelin XM1+

Any good, or are there better that I should actively seek?

I'll be running them around half way between placard and max sidewall.

[brucepick]

Lower tire pressure will cause blowout. Sidewall flexes too much and is weakened. I saw it happen on a family member's car. Owner never paid any attention to tire pressure and one blew out the sidewall. Checked the others and they were all in the 20's psi.

I'm currently running Kumho eco Solus, sidewall imprint 44 psi (supposedly a LRR tire). They were at 55 psi before the average temp here went up another 15 degrees or so. I'm scared to check the pressure now, probably 56-57 psi. I drive 600 miles weekly and have about 6 months on them now.

My winter tires are Michelin X-Ice II, rated 51 psi. I run them at 55 also. I was very impressed that I only lost about 1 mpg when I put them on last winter, vs. the Kumhos that first went on early in the previous fall. I was also impressed by how well they gripped ice. Don't know if you get any of that where you are though!

[99LeCouch]

A lot of good LRR tires can be had for the same price as non-LRR tires. Some of the better LRR tires can out-perform regular tires while still offering LRR benefits.

Besides, if you're plunking down $400-500 on a set of tires, an extra $30-50 for LRR tires darn well ought to be recouped a couple times over in gas savings. One will notice the large hit first, while the much smaller savings amounts will be lost in the shuffle.