magwheels and tires

[whokilledthejams]

Originally Posted by c0da

whokilledthejams,

Even with the compensation I still have about a 3mpg drop every tank. The tires I have are not only wider, but they are stickier performance tires. I'm looking for LRR for the next ones I get.

Gotcha. I figured I'd cover all my bases, is all.

Sticky tires will do that. I'd bet your dry traction is great, though! Even if you don't go with LRR's, a decent set of all-seasons will a good bit more efficient, as I'm sure you realize.

[c0da]

I've never had performance oriented tires on any car before and they are definitely fun to have. I guess I can't really complain too much. I push the grip of the tires when I take hard turns without slowing down to save momentum. It's love and hate kinda thing.

[modmonster]

i've just swapped my wheels. the last owner had "up"graded the stock 145 tires to 175 alloys. they weighed a tonne!

i think it will really make a difference to my mpg for several reasons:
they are thinner and more aero.
they are lighter and wheel weight is 2x important than bulk weight.
they dont stick out of the wheel hubs like the 175's so i will be able to make taped wheel skirts.
their design will allow me to install pizza pan hub-caps.

& i can sell the alloys and make a tidy profit !!!

[some_other_dave]

Originally Posted by gasti_ako

it doesn't matter if you are using 13s or 18s...

It generally will matter if you are using 13s or 18s. Unless you've got some really tall tires on the 13s, the overall diameter of the tires on the 18s will be larger. That will make your overall effective gearing taller, which will cut your RPMs/mile down, which will be good for your fuel economy when cruising at steady state.

Offsetting that (probably by more than you gain from the taller gearing) is the general tendency for the larger wheel/tire combo to be heavier than the smaller one. Which means that you lose fuel economy when you accelerate, plus (I think!) a little bit more when you go over bumps. Since pulse and glide is all about accelerating efficiently... You can see where that goes!

So there are effects both ways, but for almost everyone the larger heavier wheels are a loss.

-soD

[modmonster]

has any one done roll down tests with different tires?
that would give some data. would have to do the tests from the top of a hill from 0mph-0mph. otherwise the momentum in the tyres would affect results. i should have done this with my old tyres before the change -thinking about it.

or scan gauge highway testing?

[Geebee]

Also if you goto low profile tyres on bigger rims they will increase noise and rolling resistance.
I was all set to go that route for handling reasons pre hypermiling when I did some research and also found out that they can on a car with fairly stiff suspension deteriorate handling.
I test drove a set and found that the lack of handling in corners if the road is not perfect was real. I am running factory alloys and high quality tyres still.
Google low profiles if you have some time to kill.

[modmonster]

so i just filled up a tank and noticed no difference compared to my previous best. disappointing because i thought the 145 tyres would give a real increase. i will keep the sticky tape on my wheel arches for now though.