Hello all, I searched on the threads but found no answers. My 2010 Laramie big horn 1500 has 20" wheels stock. I have "acquired a set of 18"x10" alloy aftermarket wheels

that were operative on a 2011 ram 4x4, so I know they will fit. My question is , oh 2st let me state my tire size 275/60-20. Will I mess the on board computer up or anything by using different diameter wheels? Is there a comparable 18" tire like maybe a 265/75-18?or would I be better off to trade these 18" wheels off for a set of 20's IF i can find any?
thank you all
Mike

 

You have to make sure the whole wheel and tire combo is as close as possible to the 20" wheel and tire combo, if you want the speedometer to stay the same. But no you could put 55" tires on the truck and not hurt the computer.

 

Thanks moparfanatic21! Yeah the 265/75-18 is like .92" smaller diameter, and about 3: less circumstance so the speedo would be off a bit, but I dont think to much. How is the average fuel mileage figured , by a speed pickup or keyphaser type device? <br />Mike

 

That I honestly can't answer. The computer takes a lot into account then plugs it into a equation, then you get your fuel mileage

 

the wheel speed pickup has to play into it somehow otherwise it has no way to know how far you traveling on a given amount of fuel . . .

 

Go to Tirerack.com and plug in you year and make of vehicle and the tire size (18") and it will give you your options as to what tire size should go on the truck. Hope this helps.

 

It is part of it, but so are a while bunch of sensors.
That's good to know!

 

exactly, a lot of electronics play into the calculation, which is why the health of all the engine plays such a role in the accuracy (or lack thereof) of the estimation. the tire size change will affect the accuracy of the fuel economy readout if thats what you are trying to figure out.

 

Yes, that was my concern. But not a big issue. The 275/65r18 is VERY CLOSE to the size of the stock 275/60r20. What is more important to me is having winter tires and summer tires on separate wheels and tpms so I can just swap and go as the seasons change.
thanks for all the very valuable info
Mike

 

go to the dealer and they can adjust the tire size in the tipm. did this for my 2007 when I went from 17 to 20". speedo is accurate and delayed upshift I was having is now corrected.

you can buy a correction programmer if you need to do seasonal swaps. That is what all the guys with lifted trucks and oversized tires do.