Suggestion on Tire size change?

[ALVW3]

Hi guys,

Need your opinions - need new tires badly for my 1990 TD and my local Costco (Alberta) has a decent sale on Pirelli P4's. They can't get the stock size 185/60R14, or what I've got on there now - 195/60R14.

But they can get 175/65R14 (diameter differential= +0.92%) or the 185/65R14 (diameter differential=+3.02%). I'd have to sign a liability waiver if I go with the 185's as the dd is over 3%, so they're strongly suggesting the 175's. But I'm not sure I really want to go with the narrower tire. Any thoughts?

(They can get the 185/60's in BFG or Michelin's, but it'll cost $150-200 more, and I'm tight on $$ right now). Sale ends Sunday.

[jb86]

Michelin are great tires
Have them on my pick up truck
Quiet and smooth on the highway
Plan to get Michelin pilot exalto for my jetta
195/60/14
Got a price of $110 plus mounting
I've been told that they're spec on some BMW
There are other brands in that size but not much
It's an out dated size
15's are now more popular
Jon

[ToddA1]

I really doubt you'll feel a difference if you went with a 175/65.  Would a 185/65 fit without rubbing issues?

I'm looking to go to a taller tire to stretch milage.  I'm also looking to go skinnier (within my load rating) to reduce drag. 

-Todd

[BigVWman]

according to tire rack BOTH the 175 65 and the 185 65 p4 are 23.3" diameter! Personally i like the bfg premier's or yoko avid trz's. Last pirellis i had wore out prematurely and with a strange pattern!

[bajacalal]

I really doubt you'll feel a difference if you went with a 175/65.  Would a 185/65 fit without rubbing issues?

I'm looking to go to a taller tire to stretch milage.  I'm also looking to go skinnier (within my load rating) to reduce drag. 

-Todd

I'm running a slightly taller tire and I'm not sure it stretches the mileage. I think you lose any gains you get from running at a lower RPM on the freeway, by the fact that the tire is larger, has more rolling resistance and requires more energy to start turning from a stop. The is a little bit slower off the line.

[theman53]

Taller didn't always work for me. It seemed that if I corrected the odometer reading it was basically the same. Or there was no noticable difference that would be more than a normal 10 tank span of fills.

[ToddA1]

I'm running a slightly taller tire and I'm not sure it stretches the mileage. I think you lose any gains you get from running at a lower RPM on the freeway, by the fact that the tire is larger, has more rolling resistance and requires more energy to start turning from a stop. The is a little bit slower off the line.

I understand the "slower off the line" part, because it's effectively lowering you gear ratio.  I don't understand the "more rolling resistance" part.

I mentioned going to a slightly skinnier tire.  I'd think that a thinner tire would decrease rolling resistance and drag.  Going wider and taller would increase rotational mass and make the tire/wheel combo harder to get going, but once you have momentum, that extra rotaional mass should make the engine do less work.

Now, if you do mainly city driving, I could see where this would hinder milage.

-Todd

[billybobf]

I think that as long as you kept the width and weight down you would see an improvement, I was thinking about light weight alloys and tall skinny tires to have the same effect

[bajacalal]

I understand the "slower off the line" part, because it's effectively lowering you gear ratio.  I don't understand the "more rolling resistance" part.

I mentioned going to a slightly skinnier tire.  I'd think that a thinner tire would decrease rolling resistance and drag.  Going wider and taller would increase rotational mass and make the tire/wheel combo harder to get going, but once you have momentum, that extra rotaional mass should make the engine do less work.

Think of a tire as a flywheel. At a static state, it's not moving. To spin it, you need to add energy. If you increase the mass of the flywheel, you need more energy to spin it. It might have more momentum, but I think the logic works against you as well, to keep it going up a large hill for example. I think you are also assuming that a larger tire with a larger wheel could possibly be lighter than stock. The stock VW wheels are really light. The stock steel VW wheels are really light. I just don't think you're going to find anything that is larger and that weighs less. The aftermarket 15" wheels on my car are certainly heavier than the 13" rims they replaced. If you stick with the 13" rim, the tires are going to be costing you fuel economy. Taller tires are softer, you want tires that are thin with a large diameter wheel.

The idea of buying a taller and skinnier tire is also a problem IMO. Is there a specific size you're thinking of? The general trend in automotive design has been towards larger diameter tires, larger diameter wheels and also wider tires. That means popular sizes are now 15" rim, taller than our stock tires but also wider. The stock tires on our cars are narrow by modern standards.  If you try to find something that is both narrow and tall, I think you're going to find that there isn't much selection, or that they are more expensive, which makes the economy part of this discussion irrelevant. It's hard to even find 13" tires now that aren't low-end off-brand tires... I have had great luck with economy tires though but I haven't run them on my VW.

[ORCoaster]

Last weekend I put 155 80R 13's on my 13 inch rims last weekend for 40 bucks each.  Mounting and balancing was extra.  Les Schwab on sale.  So you can still get tall and skinny 13's at least here in Oregon.

[billybobf]

I do think for economy, taller gears smaller tires. works best

[ToddA1]

The idea of buying a taller and skinnier tire is also a problem IMO. Is there a specific size you're thinking of? The general trend in automotive design has been towards larger diameter tires, larger diameter wheels and also wider tires. That means popular sizes are now 15" rim, taller than our stock tires but also wider. The stock tires on our cars are narrow by modern standards. 

I currently have the stock size tire (175/70/13) on aftermarket aluminum wheels that came on the truck.  I was planning on using either Snowflakes or VW steelies that are both 14".  Both are behind the shed, so there's no cost involved.
 
185/70/14 would be about 1.5" taller than what I have, at around 24".  185/70/14 would be just under 25".

I also have a set of Dodge Swiss Cheese, that are 15".  BFG makes a 155/80/15 that's around 24.5" tall.  This would be ideal; a Rabbit pretty much maxes out at 25".

I've only done some quick searches with available sizes.  No matter what happens, I'm going taller than stock, even if mileage stays the same.  I want to lift my truck just shy of 2", and the stock size looks funny.

-Todd

[R.O.R-2.0]

i would run the ALLOYS. your vehicle will thank you, and you WILL be able to tell a difference.

i can tell a difference between my 185/60s on my 14" enkeis, and my 175/70s on stock rabbit 13" steelies..

the steelies drive worse. but ride SLIGHTLY better. maybe thats just the tire tho..

[theman53]

Another thought...alloys are thicker and taller than steels that I have. My snowflakes weigh about the same as the narrower and 1" shorter steels. Usually whenever you correct for the odometer difference of the bigger gear I haven't noticed much if any difference in the mileage.

[ToddA1]

the steelies drive worse. but ride SLIGHTLY better. maybe thats just the tire tho..

Does that mean the vehicle handles worse, but has a softer ride, because the steel wheel is flexing?

-Todd