lexus114

Thinking about going to 235/65-16 tires,a little wider,a tad less in height.My speedometer is already 2 miles per hour off anyway.This might help it to corner better too. Any input on this idea?

Lexmex

I am 99.9% positive I will go down to a 60 from my current 235-70-16 CrossTerrains as it would improve the acceleration a bit there (rotational mass). Still have about 6 months or so on my tires. Am taking a close look as well on tire weights, not just the size.

lexus114

Well.I thought about a 60 series,but i dont want to loose to much on my speedo,and ground clearance etc..Also,I wonder how much it will affect the computer(speed sensor)?

Lexmex

I am not sure precisely offhand on the speedometer, as it would also depend on the weight of the tire, which is something I am looking at (would like to get under 25 lbs. per tire).

BTW, the Toyota Harriers I saw in Jamaica had OEM 215-70-16. A friend who parks next to me with a new Outlander also had that same size, but I can tell you after having driven it, those corners have to be taken with caution.

With a 60 versus a 70, you are looking at dropping down about an inch, http://www.rojawheels.com/wheeltech/...Calculator.htm

AlexusAnja

Don't know if rotational mass or weight will offset the additional friction from wider surface contact, but when I went to my Mich Cross-Terrain 235-70x16 I did notice grip enhancement, but I'm losing about 1-2 mpg. in fuel efficiency.

ArcherIII

This is an old thread but I am also considering changing tire size, though slightly larger not smaller. Interestingly my speedometer over reports by 3%(2mph), and an increase to a 235/70 would be an increase in tire diameter of 3%. Net net my speedometer should be more accurate than before giving me a near perfect reading.

Tire size Diameter Rotations/mile
225 70 28.3 741
225 75 29.3 710
235 70 29.1 720
235 60 27.1 768
235 65 27.9 746

Be careful when judging MPG as the difference in speedometer also means a difference in odometer. An increase in tire size would mean you are actually covering more distance without the odometer reporting it. Result? Your MPG is probably slightly higher than your calculation would indicate. So if you are now measuring a lower MPG after increasing tire size, chances are it's not entirely accurate. I figured a 3% increase in tire diameter should lead to an under reporting of MPG of 3% (0.7MPG for example). Any other differences are probably related to actual tire manufacturer and model of tire. I doubt the actual small jump in tire size would have that much impact on MPG for the same manufacturer and model. That said a wider tire would lead to more resistance. That's why they put those skinny things on PRIUS'. I guess I'm contradicting myself but my point is a difference of 2mpg would be huge IMHO.