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How fresh is fresh?


ScottM

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I'm in need of a new front tire for my 06RT due to severe cupping at 6500 miles. Always inflated to BMW rec. pressure. I have heard tales of people receiving old tires from on-line vendors. What are reasonable expectations for dating when purchasing new tires?

Thanks.

Scott

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3 to 6 months sounds about right. Get your tires from a high voloume dealer and it shouldn't be a problem. Unfortunately the little dealers who really need sales to keep them afloat will usually have the tires with a longer life on their rack. If they're not covered in dust, I'd say your good as a rule of thumb.

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Essentially all bike tires come from offshore, and therefore it can take several months in some cases betweeen when the tire is actually made and when it arrives here at the importer, then on to the dealer. Tires do not significantly degrade, just sitting in a room temperature warehouse or dealership. So even a tire that is dated a year before you bought it is perfectly OK.

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Tires do not significantly degrade, just sitting in a room temperature warehouse or dealership. So even a tire that is dated a year before you bought it is perfectly OK.

 

I would beg to differ on that. Soft compound tires age and harden with age whether they are sold or not. I worked in Motorsports at a National level and we Air Freighted tires all over the country to keep fresh ones at all times. It would have been easier to warehouse them but the tires would become inconsistent on wear and durometer readings if they were around a while. Rarely would a tire be used the following season except for pratice or a track day for set up. Rubber oxidizes and drys up naturally with air(being exposed) that is why we all use tire dressing to keep them from checking on the sidewalls. Tires can also cure due to improper warehousing. If anyone here has worked in a large warehouse, you know how much hotter a building can be near the ceiling area. Warehouses hold in the daytime heat from the sun and can be 20 or 30 degrees or better near the ceiling and it does not cool down that much at night. The mass of the tires in a large warehouse present a lot of specific heat and this will slowly dry out tires that are new and unsold. We always would warehouse tires with softer compounds down low in the warehouse and rotate them religiously to keep the stock from getting old. I would want a tire that is less than 12 months old. The DOT number on the side tells the manufacturing date. At Bridgestone, the last 3 digits of the DOT number were the date. If the DOT ended with 237 for example, it meant the tire was made in the 23rd week of 2007. This is what Bridgestone used and I can't say that is universal. Some homework should be able to help someone decide what the batch number or manufacturing date is. Ask a true tire dealer or a national distributor how to read their DOT number for the date. These records must be kept and made public in case of recalls. The DOT numbers are always different from week to week from the factory.

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At Bridgestone, the last 3 digits of the DOT number were the date. If the DOT ended with 237 for example, it meant the tire was made in the 23rd week of 2007. This is what Bridgestone used and I can't say that is universal.

 

That is a Department of Transportation code and means the same,regardless of the manufactorer.

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Since you already got good info on tire manufacture dates, I thought a word on tire pressures was important as well since you mentioned tire pressures in your post.

 

I think if you polled the riders around here, you would find that most of us run our tire pressures a bit higher than the factory does. I for example, run 38-40 front and 40-42 rear, depending on loading and road types. You will get less or no cupping and better handling with the slightly higher tire pressures.

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With regard to tire pressures.

 

I had new tires put on my bike during the 12k service last week...

 

What surprised me were the tire pressures the dealer infalted them to.

The rear was at 42... that sounds good.

But the front was at 40... which does not coincide with that the manual states.

I know others run these pressures, so I am willing to stay with them... at least until I have information to the contrary.

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MY dealer also recommends 40/42, especailly if riding 2-up. Solo, I run 38/38.

 

The reason for running high front pressures is to reduce cupping (uneven wear along the tread pattern on the tire.

 

Here's how I think that works. The weight of the bike is supported by the tire. The tire has 2 ways to support that load. 1) The primary force is the air pressure exerting and even amount of force across the entire INSIDE surface of the tire. The second force is the spring -like force from the stiffness of the nylon cords in the tire carcass. Thsi determines how the internal force from the air pressure is distributed in various conditions. The rain grooves then create local pressure points in the tire. So cupping occurs because there is more force distributed at the leading edge of the rain groove than the trailing edge. One could argue that more pressure could cause the tire ot buldge. I think the carcass is too stiff for that to occur, but I think the increased pressure reduces the amount of contact with the sides of the tire when riding in a straight line.

 

That said, I still get a fair amount of cupping, but I think it's reduced by running higher pressures. I don't ride aggresively enough on the street to need that extra amount of heat in my tire, and the front suspension is so supple from hte telelever set-up that I don't noticed any differenec in ride.

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Re: tire pressures.

The higher tire pressures make the bike lighter, therefore there is less wear on the tires. Filling the tires with nitrogen makes the bike lighter still, with the accompanying increase in lifespan.

 

 

 

 

lmao.gif

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Re: Filling the tires with nitrogen makes the bike lighter still, with the accompanying increase in lifespan.

 

lmao.gif

If you fill the tires with Helium, does the road noise get higher like inhaling it? dopeslap.gif

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