View Single Post
Old 05-09-2022, 04:24 PM   #4 (permalink)
aero guerrilla
Piwoslaw's Avatar
Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 3,641

Svietlana II - '13 Peugeot 308SW e-HDI 6sp
90 day: 58.1 mpg (US)
Thanks: 1,191
Thanked 689 Times in 436 Posts
Hi Benjamin!
Welcome to EM

According to tire size calculator, if you go from 195/60R15 to 185/65R15 then the new tires will be ~5% narrower, slightly reducing aero drag. Also, the the diameter and circumference will be ~1.2% larger, which means that when cruising your engine will be at slightly lower RPMs.

Pumping the tires to a higher pressure will also reduce rolling resistance. I pump mine to the max pressure printed on the tire's sidewall, but if you want to start off safe then try 10% less than max sidewall.

As for chip tuning your engine's ECU, more torque at low RPMs will help reduce fuel consumption, as MetroMPG stated, but will it save enough to make up for the cost for the mod?

I would suggest you look into cleaning up your car's aero.
Also, since it is a diesel, covering the radiator/grille and insulating the engine bay will help retain heat as your efficiency improves.

How do you usually use your car? Daily driving in city traffic, high speed travelling on the expressways, etc.?
e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell

[Old] Piwoslaw's Peugeot 307sw modding thread
  Reply With Quote
The Following User Says Thank You to Piwoslaw For This Useful Post:
MetroMPG (05-09-2022)