skinny tires and handling effect

[CapriRacer]

First, you need to be aware that tire size is a minor player compared to the difference between tires.

In other words, spend most of your time looking at the difference between makes and model, and less on the size.

Second, be aware that grip and handling are 2 different things. Handling is how it feels - and I think that is where the fun is. You can have oodles of fun with low grip tires.

[user removed]

Originally Posted by Baltothewolf

I noticed a considerable drop in cornering capabilities when I got my Re92's. But then again, my mileage went up 8-15 mpg.

Which is precisely why you see reluctance from the car makers and tire makers to produce tires that can truly improve your mileage. It's a product liability attorneys dream scenario.

"How could you manufacture and make available an inferior product, when you sacrifice the customers safety for a "small" increase in fuel economy.

regards
mech

[freebeard]

BMW themselves are going that way with the i3. It has a tall narrow tire.

currently the tires are 195/60r14
and Ι am thinking about 175/70R14

What are the actual rolling diameters? The aspect ratio and width are working against each other.

When I put tires on the front of my car I chose Federal Formosa FD-1 (now FD-2) because they are available in 30/35/40/45/50/55/60/65 aspect ratio and 10mm increments in width. For years I ran 145R-15 front and 165R-15 rear. The narrow tire on the steering end resists hydroplaning and catches fewer potholes and has great 'turn-in', but downhill in the mountains the brakes overpower the tires. So now I have 165/50R-15 in front. I could have gone to 45 series, but the weight-bearing capacity was less.

[jimhs]

Originally Posted by freebeard

What are the actual rolling diameters? The aspect ratio and width are working against each other.

BND TechSource - Tire Data Calculator

static diameter is 589.6mm vs 590.6mm
afaik the actual rolling diameter depends on tire load index ,which i usually dont know it or can't choose it when i buy new tires.

[Baltothewolf]

Originally Posted by Old Mechanic

Which is precisely why you see reluctance from the car makers and tire makers to produce tires that can truly improve your mileage. It's a product liability attorneys dream scenario.

"How could you manufacture and make available an inferior product, when you sacrifice the customers safety for a "small" increase in fuel economy.

regards
mech

Yep, I really dislike lawyers for this reason, or even greedy people in general. I get in a car accident that wasn't my fault in any way and will have to deal with neck pain for the rest of my life and get next to nothing, yet someone spills hot coffee on themselves when there is a CAREFUL HOT!! Warning and they get millions. F*** the Justice system..

[freebeard]

One part in 590 is 0.16949%. Rolling diameter probably scales with static diameter, so overall gearing would be unaffected.

Frontal area would be reduced, but only between the tread and the rim, at the bottom. The contour of the tire at the rim (determined by the rim width) and the wheel cover will have as much, or more, effect. A narrower tire on the same width rim is headed in the right direction; a wider rim with the narrower tire and a Moon disk is best.

The tire I mentioned is now the FORMOZA AZ01 and no longer available in the size I got.

[PaulB2]

I had a 97 passat tdi that I wanted to "gear up" so I went with the next taller tire using approximately the same tread width. That did well, I really like the easier-running engine and better gas mileage, and the handling was fine. The next set of tires I went one step taller. I think the gas mileage probably went up again but the handling was definitely worse. I might have gone too far. However as CapriRacer notes, maybe it had more to do with the different brand than anything.

One other bad effect is that, driving on gravel roads and going around corners with potholes (so the suspension compresses), the tire snags the wheel well, and then you have to bend it back. It was a minor effect for me because the car was old, but you might not want to see that happen in a car you really like.

[jimhs]

thanks for your replies!!
i just saw that my rim width is actually 6.5in, so, i have to forget 175 tyres.
mayde i will try the 185 tires.i will see

anyway
thanks ecomodders for pimping my mpg!!!
i am averaging 6.5l/100km (36mpg) which is very good for such an old car(over 200Kmiles burning oil engine,worn camshaft,hesitating,brick like shape etc.)