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Old 07-21-2020, 02:28 AM   #1 (permalink)
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/// best tires smaller lrr tires or larger regular tires ? ///

Hi all,

I run a 2003 Volkswagen Jetta TDI 5 speed so I get pretty good gas mileage as is .

Originally the car came with 195 65 R15 ecopia 422 plus tires...

When those four were out I upgraded in size to 205 75 R15 ecopia 422 Plus Tires and noticed better fuel economy due to the larger size and lrr design.

I am currently needing to buy for more tires and I've been beating around the idea of getting even larger tires i. E. 205 75 R15. however I haven't been able to find specific Tire featuring low-rolling-resistance specifically in this size.

What do you think I should do ?

should I chance the bigger tires in the hopes that the larger diameter will potentially offset any decrease in low rolling resistance design? I currently Drive mostly highway so I am thinking the extra size would help gearing wise but worried that maybe it won't help enough because it's not a low rolling resistance design?

The tires I am looking at are as follows but I am open to any recommendations or suggestions from this List or elsewhere...

Tires I'm looking at in 205 75 r 15

Goodyear Assurance a /a
Hankook kinergy St h735
Kumho Solus ta11
Uniroyal tiger paw awp 2

The tires I am currently running are Bridgestone ecopia ep422 Plus in the size 205 70 R15.


Any and all input welcome and appreciated thanks in advance.

Andrew

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Old 07-21-2020, 08:55 AM   #2 (permalink)
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I would stick with LRR over larger diameter.
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Old 07-21-2020, 01:17 PM   #3 (permalink)
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Quote:
Originally Posted by samwichse View Post
I would stick with LRR over larger diameter.
Yes, I'm kinda leaning that way myself but I recently read somewhere that it takes a 10% decrease in rolling resistance to increase fuel mileage 1 percent...

If that's true , I'm wondering how much less rolling resistance a LRR tire has over a normal Tire because the height difference alone is about 3 % which should help with highway fuel mileage .... so I'm wondering how many more percent fuel mileage would increase with a 3% change in tire diameter?

It would be interesting if somebody did real world tests of MPGs with different tires ...
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Old 07-21-2020, 01:20 PM   #4 (permalink)
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Quote:
Originally Posted by Andyinchville1 View Post
Yes, I'm kinda leaning that way myself but I recently read somewhere
It would be interesting if somebody did real world tests of MPGs with different tires ...
The government has had a law to do just that for years, itís still not implemented
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Old 07-21-2020, 02:32 PM   #5 (permalink)
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The smaller the car, the more things like LRR make a difference. People say non-LRRs on the Insight can cost 10 mpg or so if replaced with a tire with high rolling resistance.

Weight is also a consideration, larger tires are heavier. Unless the larger tire is LRR I'd go with the smaller LRR size.
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Old 07-21-2020, 05:43 PM   #6 (permalink)
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Quote:
Originally Posted by mpg_numbers_guy View Post
The smaller the car, the more things like LRR make a difference. People say non-LRRs on the Insight can cost 10 mpg or so if replaced with a tire with high rolling resistance.

Weight is also a consideration, larger tires are heavier. Unless the larger tire is LRR I'd go with the smaller LRR size.
Aerodynamics And suspended loads can Cost more fuel economy than RR alone depending on how much larger you go.
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Old 07-21-2020, 11:40 PM   #7 (permalink)
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Quote:
Originally Posted by mpg_numbers_guy View Post
Weight is also a consideration, larger tires are heavier.
That's a good point.

On a sidenote, recently a friend asked me to do a calculation to find out how much of an equivalent to a taller ratio he would have if he changed the tyres of his truck he would get, but his goal was mostly to increase ground clearance.

But anyway, I'd much rather get the smaller-diameter LRR as it may be lighter and a lower unsprung mass being often pointed out to improve handling at higher speeds.
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Old 07-22-2020, 03:47 AM   #8 (permalink)
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You already went from 195/65 to 205/70 (or 75?). That's already a big difference and a huge tire for a Jetta. So I would stick to the same size with LRR.
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Old 07-22-2020, 11:11 AM   #9 (permalink)
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Quote:
Originally Posted by GreenTDI View Post
You already went from 195/65 to 205/70 (or 75?). That's already a big difference and a huge tire for a Jetta. So I would stick to the same size with LRR.
Hi

Yes I went from 195 65 r 15 ecopias to my current 205 70 R15 ecopias

The current tires are significantly larger than stock but seem to help mpg wise and really good for ground clearance ( I do delivery work si the extra ground clearance is sometimes helpful on people's Rocky driveways excetera).

I had thought about sitting with the tried-and-true but like with any modifying I'm always hoping for better..

The tire I am most seriously looking at for replacement is the Goodyear Assurance a/s in size 205 75 r 15

My thoughts are as follows . .. the profile is slightly higher which allows for a 3% increase in diameter changing the effective gear ratio slightly hopefully for the better..

While it's not rated as a low rolling resistance tire specifically, the specs say it does allow for up to 51 lb of inflation pressure ... compared to the ecopias maximum of 44 PSI per the sidewall. ... maybe the added allowable pressure can offset the fact that it's not specifically a low rolling resistance Tire?

Lastly concerning weight , per the specs the tire actually weighs 2 pounds less then my currency ecopias ... of course the chart also listed the ecopia has as having a maximum inflation pressure 36 PSI whereas the sidewall actually says 44. .... hopefully the info is not incorrect in other areas as well...

I'm thinking of taking a gamble on the assurances..... if they would say that there's a 30-day guarantee for satisfaction that would probably most likely just do it and hope for the best ( some places allow a 30-day exchange on tires with no penalty other than mounting and balancing cost).

Admittedly while it is exciting getting new tires and hopefully better mpgs etc ...nit's also a little nerve-wracking knowing he can go the other way
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Old 07-22-2020, 08:37 PM   #10 (permalink)
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Considering the Jetta for the very same year-model of yours was available with engines that would look underpowered from an American perspective, and they still worked, seems most likely the larger tyres won't do any actual harm to mileage.

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