Tire Aspect Ratio - Trying to Learn

Hi folks. I'm trying to educate myself on different tire sizes for my Taco and have read lots of threads here. I'm focusing on aspect ratio for starters. One of the things I'm wondering...my 21 TRD Sport has an OEM tire size of 265/65R 17. I ran some numbers in a tire calculator to see what would happen if I went to a 265/70R 17 tire down the road. It was an interesting exercise, and this is what I found out (I think lol):

• Going up to a 70 would increase the sidewall height by about 1/2 inch and overall diameter by 1 inch. So I'm thinking the truck would sit up an inch higher.
• No change in width since they are both 265s
• Revolutions per mile would go from 660 to 638 because of the 3.2 inch gain in circumference. This will cause about a 2-3% speedometer error depending on speed.
• It seems like a totally stock suspension would have no problem with the size change (no rubbing, etc)

I guess my question is, other than the change in looks of the slightly bigger tire and 1 inch raised truck, is there any advantage to the higher aspect ratio tire? My truck is a 2wd, will stay stock suspension, is a daily driver, and will be on paved roads 98% of the time. The other 2% would be your basic hard pack dirt or gravel. No off roading. Truck is used as a daily driver and occasionally tow my motorcycle on a utility trailer (< 3,000 lbs). Thanks

 

1" diameter change will only raise the truck by 1/2".

 

That's where the calculator I used was

 

You’ll only gain a 1/2” ride height gain, but I noticed a difference in cushion moving from my stock 265/70 to a /265/75. Speedometer is off slightly but hardly noticeable around town, and my mileage hit is negligible with a C rated tire. The larger tire looks better as well, I’d recommend the jump up!

 

Cool thanks! Any issues with the adaptive cruise control or any of the safety sense stuff?

 

That's the tire size I have. All works as it should. I rub a tiny bit but I have -12 offset SCS rims and a 2" suspension lift

 

FWIW, if you don't already know.

Ie 265/65R17

265 is the tire section width in millimeters
65 is the sidewall height expressed as a percentage of the tire section width
R indicates radial construction
17 is the wheel diameter in Inches.

The higher aspect ratio gives more sidewall for more flex, softer ride. This increases the Overall diameter of the tire, thereby increasing the tire circumference. So, the tire will make fewer revolutions for each mile. This will produce an accuracy error in the speedometer and odometer.

 

This actually brings up another question I was wondering about. Is there any way to re-calibrate the speedometer/odometer for the larger tires? I'm assuming the dealer would have to do it if it's possible?

 

I think so, but I'm not sure.

If it can be done, it will take a programming tool to modify settings in the truck's ECU.