I'm running them on mine ...they're fine ...I would have preferred even going to 185s for better handing still but couldn'd find any when I was buying and needed them that day (blow-out). Sorry I can't comment on effect, if any, on gas-mileage as I've never checked but keeping them at full recommended inflation should minimize this.

 

I am running them on mine and haven't noticed any real difference in gas mileage. 145s are what mine came with and now I have 175/70s.

 

What's the price diff? And, any estimates as to improved longevity of the 175/70s?

 

Wear & Price

Michelin are great tires ..but don't know if I'd spend the money to put them on these cars as there not usually known as hi-performance, hi-speed Sports Cars ...bought my 175s for $42 ea. (installed). Re: wear ...usually having lower aspect (70) means less side-wall flex and wider tread area (175) means better traction therefore should be an improvement over taller/skinnier tire.

 

My local Costco has the Michelin X-Radial in the 175 size for around $75 a tire, and when you buy four, you get a $60 gift card to Costco to use on other purchases (like gas is what I was thinking). So that's basically $60 per tire for an 80k rated tire. I think that's pretty good.

 

I bought Douglas brand at Wal-Mart for $35 each. 175/70s 40,000 mi warranty.

great in snow and wet

 

Ya, that's the price i'm seeing on most other tires that have around 40k mile warranties. The Michelin X-Radial is an 80k mile tire for only $60, so that would seem to be a better buy then a 40k mile tire for $35.

 

I rotate tires alot and maintain alighment so I usually get 60,000+ out of 40K tires. And of course I am familiar with Douglas brand tires.

 

suzuki co is recommending:

155/70 R13 75S - Swift 1.0, 1.3 SOHC
175/60 R14 78H - Swift GTI DOHC
165/70 R13 79S - Swift 1.3 4WD
165/65 R14 78H - Swift 1.6

I'm always hold up to manufacturer's advice.

here are details for changing tyres from 155/80 R13 to 175/70 R13:
the new diameter will be "-3mm". the speed will be "+1%"