Tire Size

[Mass. Wine Guy]

The 2015 Golf Sportwagen I bought very recently has 18 inch tires. I’m much more accustomed to the MK4’s 15-inch, but my understanding is that this size won’t fit the new car.

How much or how little are mpg results affected by tire size?

Thank you.

 

[P2B]

My MK4 runs 15" in winter and 17" in summer. I haven't measured any difference in fuel economy, but that could be because smaller tires are compensating for winter blend fuel.

 

[Mass. Wine Guy]

Could well be. I’ve read that smaller tires are better for winter. My car also came with four mounted 16-inch Nokian Hakkapelitta R3s. I don’t go to Vermont much during winter and have never had a set of dedicated snows. I prefer hybrids for severe weather service like the Toyo Celsius.

I’m trying to sell the four snows. Should I hang in to them?

 

[P2B]

I run dedicated winter (not snow) tires because temperatures where I live are consistently below 7C (45F) in winter. Summer tires have considerably reduced grip at those temperatures, and I prefer to switch rather than run a compromise tire year round.

 

[Mass. Wine Guy]

But the hybrid tires with the mountain peak symbol can handle moderate snow and ice very well. And they are year round tires.

 

[P2B]

Jack of all trades, master of none comes to mind.

 

[Mass. Wine Guy]

Maybe. But unless you live in Vermont, Alaska or Minnesota, they can handle the snow very well. Much, MUCH better than normal all season tires.

Maybe I’ll keep the Nokians.

 

[Cuzoe]

For whatever it's worth, my Mk7 Golf came with 16's. I can't say if 15's would work but you've got some room to step down from 18's for sure. I run 17's now.

 

[Mass. Wine Guy]

My understanding is that 15s would interfere with the brakes.

 

[IndigoBlueWagon]

15's fit fine. Here's my car with my newly added 15s.

Not on this car (because I don't plan to drive it much in Winter) but on my MKIVs I have Michelin Cross Climate IIs and Nokian WR-G4s. Both all seasons with a severe winter rating. I haven't use the Nokians to speak of in winter, but they're a great all season. And the Michelins have been on my Wagon for 2+ years. They're good in the snow, and perform very well in dry and rain. And no FE hit.

Given the diminishing amount of snow we now get in eastern MA, I think these are a good option. Unless you drive up north regularly, I don't think dedicated snows are needed here any longer.

 

[Mass. Wine Guy]

I have Toyo Celsius on two others. Big believer in these hybrid tires.

Would/could tires smaller than 18 inches increase fuel economy? If so, how?

 

[oldsoul]

Here's my experience with a deleted mkvi Jetta sedan. I've run 17's, 16's, and 15's. Tires from 235 down to 205 wide. I've seen a bigger change in MPG's from outside temp changes than tire/wheel combos. I see temps from around 90 in the summer to -40 in the winter, so temp range is pretty extreme in my case. I run true snow tires in the winter as well. Still temps affects economy more.

Short answer to this question is: go with what you like, and suits your needs. The impact on economy, simply, is too small to be a concern.

That said, if economy is your ultimate goal, then go with the lightest, narrowest combination you can. Generally, this will mean small wheels, big sidewalls, and pretty narrow tread. I would warn against going too narrow as safety and performance WILL suffer at some point.

I have found that going with the smallest stock wheel size, usually the size of your spare, and the appropriate tire size (you can find that at https://www.wheel-size.com among other places) will get you the best balance.