http://www.tirerack.com/tires/...e.htm* ... ****"Width x Aspect Ratio = Section Height x 2 = Combined Section Height + Wheel Diameter = Tire Diameter
Example...185/60R14 85H or 185/60HR14
185mm x .60=111mm x 2=222mm + 355.6mm(14")= 577.6mm or 22.74" "***************************How is 111(2)=222+355.6 ???
Is the Tirerach size guide wrong?
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Mayhem_J30
- Posts: 2643
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- Car: Ummm...My Car
- Location: Louisville, KY
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Mayhem_J30
- Posts: 2643
- Joined: Tue Apr 30, 2002 2:00 am
- Car: Ummm...My Car
- Location: Louisville, KY
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szh
- Posts: 15932
- Joined: Tue Jul 23, 2002 12:54 pm
- Car: 2018 Tesla Model 3.
Unfortunately, no longer a Nissan or Infiniti, but continuing here at NICO! - Location: San Jose, CA
TgduMg wrote:diameters varied about four tenths for the same size tire. I know that there is often a little variance between manufacturers but I just figured it was a typo.
May not be typo's necessarily. The effective rolling diameter is often different from what the raw math calculations will show. This is due to sidewall flex, section width, tread width (affecting the shape of the walls), etc. This means, for example, that one real way to gauge speedometer error is to use the "revs per mile" numbers - of course, you have to assume that there is no typo there!
When looking at a tire spec at Tire Rack that looks incorrect, I try go to the manufacturers web site for more info. Needless to say, the manufacturers sometimes typo it too at their web sites! On occasion, they change the tire specs (like load index, max pressure, etc.) and forget to update their web site info.
Take everything with a grain of salt and verify the numbers (for things like load index and max pressure) on the side of the tire itself. There the info is required by Federal law to be correct (but not guaranteed!)
Sigh ...
Z
This past Summer I was looking for some Continental Touring Contact AS in 215/60TR16 for a 02 Taurus (my moms daily driver). I could not find them locally but at the time the Tire Rack had them for $49. Today they are $57 but anyway, there is a lot of tire data to input with all of the different types, sizes, and brands that "The Rack" and other online tire retailers handle. Since I know section width x aspect ratio divided by 25.4 x 2 + rim size, I can be forgiving when I come across a typo. Well, when I pulled up the Tire Rack spec chart on the Continentals it listed the overall diameter of the 215/60TR16 at 26.1. On the 225/60TR16, 26.1. Gotta be a typo. I look up the Potenza RE92. 215/60VR16 at 26.9. Gotta be a typo. Especially when the 225/60HR16 is at 26.5. But wait, it gets better. RE92 225/60TR16 98T SL Honda. Diameter listed as 25.6. The OEM size for the 98-02 Accord V6 and the 99-03 Acura TL with 16 inch wheels is 205/60R16 for which the diameter should be around 25.6. With a load index of 98T the tires listed are likely for a Honda Odyssey at anywhere from 26.5 to 26.8. Next. Michelin Energy MXV4 Plus. 215/60R16 listed at 26.4 compared to the Continentals 26.1, but not necessarily a typo taking into account the manufacturers variances (BTW the RE92 94V and MXV4 94V were OE for the FY33 Q45). The MXV4 Plus 225/60R16 is 26.8. Several months have passed and the charts still have not been corrected, but I haven't notified them about it either. Like they would get right on it. Okay. Something else that I wanted to touch on. When a used car dealer or even the previous owner will have tires put on, mistakes are sometimes made when the tire retailer looks up the size in the tire chart for the car or just puts back on it whats on it. Example. A co worker of mine bought a 95 Mustang GT some years ago and it had some aftermarket Prime 5-stars with 225/50R16s on it. I told her that it was supposed to have 225/55VR16s on it. She didn't believe me at first. When she bought replacements and again the 225/50s, I made her pull out the owners manual. Don't doubt TgduMg. Another example. My 98 Altima GXE had 195/65TR15s. I had it in for service and my service writer told me they could get tires cheaper than I could so I had him send my car across the street to have some Toyo Proxes tires installed. When I picked up my car it had 205/60HR15s on it. No big deal as the diameter is not that different from OEM and I thought they just probably were out of the 195s. The Proxes was available in both sizes. The next time I was out there I asked the counter guy at the tire dealer why he went with the 205s instead the 195s. He showed me the tire guide. It listed the replacement as a 205/60R15, but for a 98 SE not a GXE. If he would have taken the time to look at the column under the one he saw it showed 195s for my car. Anyway still no biggie. However, I noticed that some 97-98 Q45s at the dealer had Proxes 225/60HR16s on them and asked why he put them on instead of 215s. Here comes the BS. Oh, they told me to put a taller tire on those with an H rating for ride and handling. Yeah. I checked. It was really because Toyo did not have a 215/60R16 Proxes available at that time. They still may not. I dunno. And if I had a dollar for everytime I saw a 1st Gen Q45 with 215/60R15s, 205/70R15s or 205/75R15s, well I'd have a little more money. I know this is a long post which is one reason it has been awhile for me to re post on this thread cause I knew it would be a long one. So always remember this, some sales people don't always have the right answers but just something to sell. So buyer beware. I'll check my tyos later....Danisiti 1...