skinny tires and handling effect

[jimhs]

hello ecomodders!!

it is time to buy new tires for my bmw E30 318i
currently the tires are 195/60r14
and Ι am thinking about 175/70R14
in order to bring revs down and decreace rolling and aerodynamic resistance.
I tend to enjoy my car on curvy roads and hypermile elsewhere in order to balance my fuel consumption.
my question is about lateral grip,how bad can it be??
and what about FE with this tire conversion???

average mpg is 33-35 mpg
mods: 40-45 psi,grill block,air dam,belt fan delete(on winter),30kg weight reduction,folded passenger mirror(except city driving)

thank you in advance!

[Hypermiler1995]

I'm not an expert, but I have looked into this, The Donkey CRX claims 1.5-2mpg, so expect 1mpg from thinness, plus maybe 1mpg for height, and expect the tires to be more likely follow any unevenness in the road, you might feel bumps more too.

[mcrews]

LOOK for my posts on my 2002 Q45S with factory 245/45/18. I went to 50's. didn't notice any difference in handling.
Really depends on the stickiness of the rubber.
The 5+% increase in diameter helped my mpg, especially on the highway.

[niky]

Pumping up the tires extra hard just for those canyon-carving sessions can mitigate or eliminate any loss of grip due to the sidewalls rolling over. And let's be honest, coming from a 195/60, you'd already have a lot of that happening anyway, unless you're already running high pressures!

When I get a test unit with ultra-tall tires, I often find myself sticking 45-50 psi in when I want to have some "fun"... Not a substitute for better tires, but at least the handling gets more predictable. Some police instructors have suggested 60 psi... but then they're running old-school balloon tires on two-ton ladder frame sedans, so...

Any loss of grip due to the narrower section width is either marginal or non-existent, depending on who you ask, and likely the tire compound itself will have a greater effect on lateral grip.

As said, though, the tires will be more likely to follow the road. They'll affect on-center stability on the highway and might feel a bit more tippy. Pump them up hard and the wandering is exacerbated, in most cases... but I don't know if this is dependent on the cars I've had these tires on, so YMMV.

[gone-ot]

Skinny tires are like "high-heels" when it comes to cornering and handling.

[2000mc]

i would put finding a tire model, and desired diameter above finding a narrower tire, if you can find all three, then great. I wouldn't be surprised if the best tire size for mileage on your car would be the biggest diameter that doesn't hit or rub. As an example on tire model without any considerations but mileage, I think a 185/65-14 Goodyear fuel max would beat out every available 175/70-14 here dispite being a fraction shorter and wider.

[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.

[Frank Lee]

Originally Posted by Old Tele man

Skinny tires are like "high-heels" when it comes to cornering and handling.

The old Porsches did pretty well on skinnies.

But I don't think 20mm width will be the biggest variable with any tire change.

I went from 235 to 265 and didn't notice more cornering capability- but then I wasn't looking for it either. So for ordinary driving it didn't matter but for exploring the limits it might have.

[markweatherill]

Originally Posted by Frank Lee

The old Porsches did pretty well on skinnies.

Who told you that? James Dean?

[oldtamiyaphile]

Originally Posted by markweatherill

Who told you that? James Dean?

The history books. Lemans, Targa Florio, Rally, all conquered on skinny tyres. The 550 ran 155's IRC.

People confuse 'handling' with grip. There's no reason why a car on skinny tyres can't have 'perfect' handling while one on a set of fat racing slicks is a dog. The car on slicks might still be faster, but that's because it has more grip.