P195 60 R15 Tires

[redlegs75]

Hello guys,

I purchased a couple of weeks ago a set of Uniroyal P195s that replaced my Yokohama P185s. So far I have noticed that my gas mileage is down 3 to 4 mpgs. Would those P195s make that much of a difference in my fuel economy or is this a fluke? I have only filled up 3 times since purchase and I drive 160 miles to work and back each day so 3 to 4 mpgs is pretty important to me. Suggestions?

Thanks

[CrankyOldMan]

Plugging the numbers into a size calculator, it looks like the diameter of the 195's is a little larger, about 0.5". That would give you a lower RPM at cruising speed, but require more gas to accelerate. The "best" RPM for efficiency should be at peak torque output, around 4200 RPM. If you're turning less RPMs, that means less torque at a given speed, as well as poorer economy. It could also be a difference in the rolling resistance of each tire. Too many variables to say for sure, but it's a strong possibility that it's not a fluke.

[why?]

i'd say it could be the tires, but also when did they switch to winter gas in your area? That has a large effect as well.

[kimona]

I don't think its tyre size... especially if your commute is at highway speeds.

[redlegs75]

Hey guys,

I have an update in my fuel mileage with the P195s........I just got gas today and I got 38.05 on my last tank.......makes me feel a bit better.....I got that last tank of gas at BP........dont know if that makes a difference....

Thanks

[why?]

bp has been heavily advertising additives that help gas mileage, so that could be. plus you could be more aware of it, and that could mean you are paying more attention as well.

[redlegs75]

I have logged my mileage evertime I have filled up since the car was new in March of 08. Have never got less than 35 miles per gallon. I will keep tracking the mileage with the new tires and keep you posted.

[toad]

^curious to hear the results. i made the switch to the identical tire size a couple years ago. i think it looks better in our '4x4' wheelwells, but i never really thought about the effect on gas mileage until now. i did notice a smoother ride, but that might just be from upgrading to a better quality tire!

where in indiana are you located? we've got a few members scattered throughout the state. a couple of us are in the indianapolis area.

[redlegs75]

I am located in Mooresville and I commute to Muncie everyday. I have mostly interstate driving so it is really not that hard of a commute even though it is almost 80 miles one way. I really like being in my Yaris, I have the manual transmission and despite what I read in the reviews, I do not by any means think it is a boring car at all! It is fun to drive and has no problem holding its own on the interstate for speed. A vast improvement from my college days when I drove a Chevy Chevette....ha ha.

What part of Indy are you from?

[redlegs75]

One thing I am thinking of doing is upping my tire pressure to maybe 38 lbs. Maybe that will also help.

[toad]

westside. i drive a light blue sedan. increasing the pressure may help, but i recommend checking out the fuel economy sub-forum on this site. LOTS of great info there if you're wanting to squeak out every last bit of mileage out! good luck!

[thebarber]

keep in mind that your odometer will be off too....you're actually going to travel about 2% farther than you think you are...not sure that helps you much.

[Shroomster]

Wife and I have 195/60r15 goodyear eagle gt on our civic and yaris.....she consistently gets same mileage around 28mpg (only travels about 6 miles round trip) before and after tires (used to have p195/55r15)

[brg88tx]

you have to take the miles traveled and multiply by 1.0198 to come up with the actual miles traveled since the tires are 1.98% too big. then divide by gallons used.

[redlegs75]

Will my odomometer and speedometer be off if I am using the P195 60 R15 tires?

Thanks

[kimona]

Will my odomometer and speedometer be off if I am using the P195 60 R15 tires?

Thanks

Not necessarily. The speedo is not accurate out of the box.

I went from OEM 185/60/15 (23.7") to 205/50/16 (24.1") and now my speedo is dead accurate.