What diameter tires are you using at the moment?
 

I need some back up data on ecomodders tires when I will go to nokiantyres to talk about some special purpose tires which I will need on my Lupo 3L. I suggest that they would make about 5 different sizes with about 8% diameter steps :/.

You can legally change the diameter of tire 5% to each direction in EU, is it the same in the states?

Oh and the new very low rolling resistance nokian tire is not yet on the market ;).

25.5"

25" or so, the ones the came on the car OEM. 215/55-17.

25.07" (P205/50-R17). OEM were P185/60-R15, 23.7" diameter. New tires are 5.31% taller. US mfrs don't recommend going above 3% taller.

...OEM on our 2011 Cruze LTZ is P225/45R18 on "flangeless" alloy rims.

Vekke -

195/65 15, one size up from stock, about 2+% larger diameter and 1 lb heavier than stock. I don't know of a specific law in the USA that prohibits tire size change. It's more a physical thing of fitting in the wheelwell. I could have fit two-sizes up from stock for a 4% larger diameter, but the tire jumped to 3+ lbs heavier.

CarloSW2

In the US we can do pretty much what ever we want with tire size as long as it with in reason.
On my car I run P225/60R16.
Taller and narrower that the dead (245/45) 16 inch OEM size my car came with.

On the truck I use 31x10.5R15. That is between 2 to 3 inches taller a little wider than what it left the factory with. I went taller for less rotations per mile and wider for the load rating.

I'm running the very popular 205/55/16 24.87 in 631.69 mm diameter
Can't do a range of tyres in Europe without this size.
(As an OEM alternative to the stock 195/65/15 24.98 in 634.49 mm.)

In Belgium, we're limited to - 2 % and + 1,5 % differences in tire diameter.


It definitely needs testing then. :cool:

Dumb question everyone,
has anyone noted a significant gain in MPG's due to lower cruising RPM's with bigger wheels, in spite of possible losses in aerodynamics and gains in weight?

Yes. Tall tire test. Note page 1 of that thread shows the heavier, less aerodynamic wheels/tires don't give significantly worse performance than the OEM stockers.