I recently purchased a 2000 Foreman 450S with original front tires and Maxxis Zilla rear tires. One of the front tires went flat due to a bad valve stem, so I removed the tires to have both valves replaced. It turns out one tire is an inch or so larger in diameter and at least an inch wider. My original assumption was that someone took a 10-12 tire off the rear and put it on the front. I checked. Both tires are Dunlop 401C and say 25x8-12! Anyone else ever experience this? What gives?
different sized AT25x8-12 tires
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first off welcome to the site
a few things come to mind here for me
one, the tires are from different runs at the factory. and maybe they changed something, say 2ply to 4 or even 6, there should be a date or date code on the tires to help here
next will be, if the wheels are of different width, say one is a 6 inch wide and one is a 8 inch wide, it will effect how tall and wide a tire sits when mounted
next is he air pressure the same in both tires?
its not UNCOMMON that an atv tire from any maker is NOT true to its size on side wall, , and not the same from different model tire from same brand
many tires are known to tun tall or shorter that size on side wall
if all things on your tires check out to be the exact same tire and are of different heights and width, I suggest emailing the OEM and see what they can maybe do to help you, as on a 4x4 atv, you should NOT have different sizes in tires, it can cause drive-line problems or damage
a few things come to mind here for me
one, the tires are from different runs at the factory. and maybe they changed something, say 2ply to 4 or even 6, there should be a date or date code on the tires to help here
next will be, if the wheels are of different width, say one is a 6 inch wide and one is a 8 inch wide, it will effect how tall and wide a tire sits when mounted
next is he air pressure the same in both tires?
its not UNCOMMON that an atv tire from any maker is NOT true to its size on side wall, , and not the same from different model tire from same brand
many tires are known to tun tall or shorter that size on side wall
if all things on your tires check out to be the exact same tire and are of different heights and width, I suggest emailing the OEM and see what they can maybe do to help you, as on a 4x4 atv, you should NOT have different sizes in tires, it can cause drive-line problems or damage
Thanks for the help. My guess is that tire pressure actually affected the size of the tire. I wouldn't think so logically, but that may be the case. Over a year ago when I suspected I was losing air through the valve (18 year-old valve), I increased the pressure in that tire to try to seal the valve: the higher the pressure, the tighter the seal, right? Over a period of time, that extra pressure must have actually increased the size of the tire, especially over the summer months when things are more pliable. That's the only thing that makes sense. Thanks again for the suggestions.
Way back in my early racing days on the short tracks we used to "adjust" new tire diameters according to where the tire would be put to work on the car. We'd buy a whole bunch of new tires (meeting the sanctioning body rules) at once, mount them all on wheels then measure each one at identical pressures. Every tire was then marked and sorted according to its diameter and at that point we decided where each tire would be put on which corner of the car. Then the largest group of tires were blown up as hard as we dared... and put out in the sunshine on a rotisserie rack to get super hot and stretch. After a couple days baking time on the racks each one was brought back indoors and cooled, purged of air using nitrogen, then refilled with nitrogen to an average pressure we usually ran on Rt Fronts... then measured and remarked with the adjusted tire diameter and its intended location on the car.
We then "adjusted" our tire diameters to stagger the remaining two corners: Rt Front. Rt Rear, Lt Front all were pre-stretched at least a little to get the desired staggers... The Left Rear tires were all sorted out in the 1st step... the only ones that did not get stretched, because Lt Rear is the smallest wheel on the car (run almost flat, 8-12 lbs PSI) in short dirt track racing. It was common to find the Rt Front more than 3 inches taller on our cars in those days, than the Lt Rear was. Shocks & spring rates were staggered for each corner as well, then the car was scaled and percentages & wedge adjusted for each heat/feature race in our pit.
Every tire can be stretched by high pressures and heat, some just stretch a bit more than others do.
We then "adjusted" our tire diameters to stagger the remaining two corners: Rt Front. Rt Rear, Lt Front all were pre-stretched at least a little to get the desired staggers... The Left Rear tires were all sorted out in the 1st step... the only ones that did not get stretched, because Lt Rear is the smallest wheel on the car (run almost flat, 8-12 lbs PSI) in short dirt track racing. It was common to find the Rt Front more than 3 inches taller on our cars in those days, than the Lt Rear was. Shocks & spring rates were staggered for each corner as well, then the car was scaled and percentages & wedge adjusted for each heat/feature race in our pit.
Every tire can be stretched by high pressures and heat, some just stretch a bit more than others do.
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