I was wondering if the following tire size change would cause any issues.

99 Tacoma 4x4 5-speed. Original tire size was 225/75/15. The truck already had 16s on it when I bought it. It has 265/75-16 tires on it. This seems to throw my speedo off 5 plus MPH at 45MPH and up. Tires are about wore out and wanted to stay with 16s but put a tire on that would bring my speedo back closer to reading correctly.

I found a tire size calculator online and punched some difference sizes in.

According to the calculator comparing what I have now to the stock tire size, if my speedo reads 45, I will actually be doing 50.35MPH.

If I change the middle number and make it 265/60-16 and compare that to the factory tire size it says when the speedo reads 45 I would actually be doing 45.37MPH which is much closer.

Right now with the 1" bigger rims and the 75 sidewall height my tires rub when turning. I figure dropping the sidewall height from the 75 to the 60 could resolve this problem as well as the speedo issue. Am I thinking about it right? Would there be any other issues going from a 265/75/16 to a 265/60-16? Is there a better combination that what I have said?

I do have access to a set of 15" rims I can have if it would be better to just go back to factory tire size, I would have to look at them again to make sure I would like how they look. I do a lot of towing in the summer if that makes a difference in any suggestions. Thank in advance for any insight.

 

I doubt your factory tire size was 225/75r15. Sure that's what the sticker on the door says, but it either came with 31x10.5 r15 or 265/70r16. The 265/75s will make the speedo read slow as they are larger diameter tire. The rim size has zero effect on your speedo. Only the outside diameter of the tire. You should use your existing wheels and get some 265/70s, or 245/75s. 225s look silly on a 4x4 and would make your speedo read fast, most likely.

 

Oh ok. I didn't know the door sticker was generic and did not always apply to the actual tire size on the truck. Some researching after I read your reply and I seen that.

So as far as the options you suggested between the 265/70 or 245/75s, which would you suggest? I do quite a lot of towing in the summer and haul firewood out of the woods in the winter if that matters.

 

245/75 comes in a 10 ply e rated tire if that matters to you. I had 245/75 c rated Firestone destination on my old 4Runner and they were cheap. 265/70 is a less common size and is available in a p (passenger) rate and lt rating too. Much to consider.

 

Is the spare tire any indication of tire size that came on the truck? I just looked at the spare and its a 225/75-15

 

Yes a full size spare was included with the truck so you may have had 225 on it. I would look at 235 75 and you have a lot of options in that tire size

 

Well I want to keep the 16" rims. I just downloaded a speedometer app on my iPhone and I am about to go out and drive the truck and see what the app says. If it did indeed come with 225/75-15, then according to the calculator when my speedo says 45 I should be going a tad over 50 with these 265/75-16s. Depending on how good Toyotas calibration was from the get go.

I have done a lot more reading the last couple days regarding the 265/70s and 265/75s. Some said the 75s made there speedo more accurate. Mine seems to read slow.

I usually get around 13MPG when I calculate mileage according to my odometer. Tire calc says the difference in revolutions per mile between a 225/75-15 and 265/75-16 is 10.6%.

So my last tank was like 186 miles. If I factor a 10.6% difference then that would add another 19.716 miles to that tank. I just want my damn speedo to be right, I am OCD about that type of stuff. Plus I run a business and write my mileage off at the end of the year so the last 2 years I actually wrote off LESS miles than I actually drove which hurt my bottom line.

 

From the factory all mfg like to make their speedo read a bit fast. Among reasons are that this helps inflate their gas mileage (appearing to go further than was really traveled), and reduce speeding tickets, and there are some more I can't recall nor can I cite a source. If you're at your stock tire size, going up one size may make it a little off in the other direction, or it may make it more accurate.

You could go on a trip of a known distance (or use a gps) to record the miles you traveled, and then check against your speedo. That would give you the percentage you're off too. The more miles you can go on this trip, the more accurate the percentage. You can figure your tire size with that info.

 

I used a GPS to see what it said I was going MPH wise compared to the actual gauge cluster. Compared to the GPS my gauge cluster was reading about 3mph slow at around 45-50mph. So going from a 265/75 to a 70 might make it read about right. The GPS seemed super accurate as I tried it out in my 2008 Civic and it read dead on to what the speed in the car said.

I also checked back on those 15" rims I can have. My Dad got them a long time ago and thought they were for a Tacoma but turns out there not, to bad because the are actually alloy instead of steel. They are currently mounted with 32x11.50-15 tires and I took one of mine off and holy smokes, I did not weight them but there was a pretty big weight difference with the alloy wheel/tire combo being way lighter. But I can't use them because there not the right offset, etc. The tires stick out WAAAY past my fenders. The center cap area is so thick that the lug nuts have a shank on them to reach through the center and get to my studs.

Also I will do the mileage thing vasinvictor suggested and see what I come up with.

 

After seeing how heavy my steel wheels and 265/75 tire combo is, I have been looking at alloy wheels to reduce weight. The tires I have now are E rated so probably heavier than a lower rated tire so I am not sure how much of the weight is from the tire and how much is from the wheels but they are HEAVY.

I have also decided to go with a 245/75-16 tire.

I found a guy on craigslist not far from me selling some 16" alloy wheels from a 2009 Tacoma and they are fitted with Nitto Dura grapplers that look to have a lot of life left on them. For his asking price I can pick up the alloy wheels with the tires for less than I can just get new tires so this is a great deal to me.

I know most everyone loves the big tires, I love the way they look but for what I use the truck for, get up and go and any additional MPG I can get is what I am looking for. This thing only sees 4WD engaged a handful of times in the winter when I haul firewood out of the woods.

I think the 245/75s will still look good anyways. Won't fill the fender well as much as the 265/75s but I am going for function over looks at this point.

From what I see the 2009 wheels will fit