285 35 19 Verses 245 45 18

[87vertgt]

Any idea if it would be benificial ?

thanks

[Beau]

A 285/35/19 has a diameter of approx. 26.85 vs. the 245/45/18's diameter of 26.68. Since that is a verfy slight (0.6%) increase; in that regard there may be a very slight plus to the 19". On the other hand, 245/45/18 is narrower (by 40mm) and the 18" wheel should weigh a bit less than the 19" wheel, giving a slight advantage to the 18". I would consider is a push.

On the plus side, 18" tires are usually much less expensive than are 19" tires.

[MetroMPG]

The forum's tire expert (CapriRacer - tire engineer) will tell you that rolling resistance outweighs other minor variations (eg. weight, circumference, width).

So unless you know the tires have exactly the same rolling resistance (in which case I'd say the narrower ones would win out through lower aerodynamic losses) the only way to tell would be to test the 2 sets of tires against one another.