Quote:
Originally Posted by busypaws
Haven't done any A-B-A testing but I didn't see it with my 95 Toyota PU. Stock tires are 195/75/R14. First time I changed to 205/75/14. So I went a little wider and a little taller. Did not see a change in fuel. Then 40K later I went 215/75/r15. So I bought new steel rims. Now my Spedo is off by 8% so I have to remember that when going through the auto camera speed traps. Again no noticable change in mpg. I can say that the interstate here in AZ is 75 and now I can go 65 on spedo which is really 70 and not feel like the engine is too high RPM. Also 70 in 75 zone doesn't piss off too many people.
I think the real answer is trying to find taller tires that don't also increase width. If you are already at 75 ratio then you can't really go any taller without also going wider and heavier.
|
Not trying to be a nit-picker, just trying to help you avaoid a ticket...Your speedo is off by 8.5% with the 215/75/15s..an indicated 60 would really be 65.1.....my question is, when you figured your mpg did you also figured in that you drove 8.5% more miles than your odometer said? Rolling resistance ant wt will affect all vehicles, less so on big, heavy models. On my 3 banger Geo I went from the stock 13s (max psi 35) to 195/50/15s (max 51 psi) AND GAINED 8 lbs per corner! I had also removed an extra 32 lbs of interior wt so overall wt was the same. The best mpg still stayed at 57 due to higher psi and less rolling resistance. Now I put on a new set of 155/80/13s (OE size) but with higher psi AND lighter rims to knock off 40 lbs of rotating wt and my last 4 tank fulls have all been in the low 60 mpg range!
