[Neocacher]

Just purchased a 2004 4WD in decent shape for a decent price yesterday. To make a long story short, upon inspection after I paid and came home, I found out that the tires (50% tread left) were undersized by over an 1 1/4" in diameter. Tires are 235/60R16 (27.1" diameter) and originals are supple to be 225/70/16 (28.4 " diameter). I don't believe seller misled me on purpose, he probably either didn't know or remember to tell me as it was his wife's car I bought. Tires were purchase at Walmart over 2 years ago and have exceeded the mileage warranty most likely., again, that being said there is still about 50% tread left.

I really don't have $500 for new tires. Other than the obvious speedo error, higher RPM, are there any safety issues I should be aware of? Speedo is off around 4.8%. Tires are probably good for another 20,000 miles.

 

[Ralph6410]

I think you are just observing simple math. The tires have worn and thus the circumference is less. You are going to loose ~ 1/2 an inch for every 3/16 of wear. For what it is worth.. the diameter will change with air pressure.. which changes as you drive. As well the tire will increase in diameter the faster you drive.. No big deal, it is part of all the variables that exist.

 

[Rolling Thunder]

With your current tires (when new) when you are doing 60MPH on your speedometer you are truly doing almost 63MPH. Other than being aware of this and adjusting for it if necessary there is no problem.

 

[Neocacher]

It's not simple math. Look up the size difference on a tire chart. Regardless, I went to Walmart this morning and they gave me the proper size tire at a pro-rated price, which satisfied me. Running tires 2 sizes too small can be dangerous, as well as cause other issues. Maybe I am just too anal, but a mistake was obviously made when these tires were originally purchased.

 

[Neocacher]

Rolling thunder, you have it backwards. Because the tire rotates more often in a mile, the reading on the odometer is higher than you are actually going.

 

[Rolling Thunder]

Rolling thunder, you have it backwards. Because the tire rotates more often in a mile, the reading on the odometer is higher than you are actually going.

Neo,

You are correct, I had it reversed:

~57MPH+ true while showing 60MPH on speedo.

 

[AVConsult]

Assuming all 4 tires are identically sized, if you don't mind the speedo (and cumulative odometer) error, it won't effect ABS braking, traction control or general driving. If it were mine, I'd drive it until whenever I normally replaced tires.

 

[Neocacher]

Walmart took the old tires back and pro-rated them for me. They didn't have to to that, but they did. Outstanding! New set of General Grabbers STX for only $250 after my discount.