Thursday, June 4, 2009

More Tires

What follows is my response to a post by Dr. Wrench about tire pressure. I wanted to repost it here not because I think I know it all, but because it is very important and to the best of my knowledge accurate. Also, second only to your brakes your tires are the most important thing on your bike for your safety. This is only slightly edited because I’m too lazy to do it all again. So if it seems I’m talking to a third party it is because I was responding to a response in the good Dr’s. post. To understand this it might be worth your time to read the Dr’s. post if you haven’t done so already. With that out of the way…

fasthair said…

I'll add my two cents here. As mentioned weight is also a factor. If you are going to be riding two up with lots of stuff (face it if your riding two up number two SHOULD be a female and they always have to bring lots of stuff) Then max out the pressure. If you read your owners manual (yah I know who does that?) it will even state this.

And Mr. Baron with all due respect you got the logic wrong. As you might know I work on Mercedes-Benz for a living. During service of these fine high performance machines I always check and set tire pressures. Each model has different settings. How do I remember all of these settings? I don't, I look in the gas door. Guess what? I quote, "for driving 100+ mph + 4PSI, for warm tires add + 4PSI."

Here is why your logic is wrong. The extra pressure actually helps the tire hold it's shape and NOT expand as much as if it had lower pressure. Just as someone else said, lower tire pressure will also affect the contact patch of the tire, i.e. the shape. Now before you say "but drag slicks only have about 5 to 6PSI" remember this, these tires are designed (Edit: and sometimes don’t last even the quarter mile because of this) to run at these pressures. Plus have you seen how that tire looks at speed? The back side (in direction of travel) is almost flat against the wheel and it has grown several inches in size. This is all the effect of low tire pressures. There is also this. Lower pressures cause higher tire temperatures too. Why? Friction. This is why properly inflated tires give you better gas mileage, less friction. Less friction equals less heat. A under inflated tire will actually fail sooner (Edit: because of heat… Ford Explore anyone?) then an over inflated tire because of high heat. Which all add up to longer tire life. So in the end, for high speed riding, max it out.

So after saying all of this can you guess where I run my tires? Yup, maxed out, 45 rear 42 front. For all of the reasons above but also because the bike does handle better and it does promote longer tire life.

Last thing for you others who don't check your tires. For the love of God please do so! Not only will it be safer for you but you will save money!

Of course your comments are always welcome.



Baron's Life said...

As I mentioned on my post over at Mr. Wrench back then I ride at the high end because of the ride comfort and the fuel economy, but have been always wondering what if...thank you and Dr. Wrench for clarifying this for me.
Cheers and ride safe everyone...too many mishaps out there

mq01 said...

i resemble that remark ;)

mq01 said...

NOT... LOL! actually i will have you know mr fasthair that i pack quite light thank you very much... LOL... and my tires are maxed. thank you. great and much appreciated info!

fasthair said...

Mr. Baron: First I wasn't picking on you. But I could tell from your comment you didn't really understand what is going with tires. That is why I wrote this and I'm very glad that this helped you understand the dynamics of what a tire goes through. That was entirely the whole point of my post, to help clear things up.

Ms. M: See I knew it! Oh wait. OK if you say so! :)


IowaHarleyGirl (Stephanie) said...

Mr. Fasthair...Not all women have to bring everything plus the kitchen sink. Last year Dan brought more to Sturgis then I did. How bout them apples my friend???? LOL

Ann said...

I used to work at a crash-test facility here in Phoenix. We did a lot of testing on the Ford Explorers with those Firestone tires. I know it's not a bike, but the results were scary as hell. Always check your tire pressure!

Willy D said...

Welcome back!

fasthair said...

Ms. IGH: Ok if you say so too. Short funny story. My buddy his wife and I set off on a two week vacation. They look like the Beverly Hillbillies going down the road because she has some much sh!t going along. She has 23 pairs, count'em 23 pairs of shoes with her, God only knows why. The second day we wake up and get ready for showers. Guess what she didn't pack? Yup not a single towel or wash cloth in all of that sh!t! I just laughed as I tossed them one to share for the trip. To this day she still packs like this and we still laugh about this trip every time before we take off.

Ms. Ann: I remember you telling me this job you had. I thought of it when I made the comment. I bet that was kind of fun job crashing stuff all day long.

Mr. D: Good to be back. Nice to see you again too!


Baron's Life said...

Fathair... I know you weren't picking on me. We are a community and as such...we help each other first and foremost... Thanks Buddy...Cheers

Baron's Life said...

mq01 I'll gladly carry your luggage sweat

Baron's Life said...

Steph...taht's hard to ya girl

RickNiekLikeBikes said...

Great advice man. Some days it's hard to remember all one needs to do before riding, but I can't mess with my safety.

Jack Riepe said...

Dear Mr. Fasthair:

You are so right about the importantce of tire pressure. I'm running a pair of Avons on this K75 and I've got close to 11,000 miles on them. (They are getting replaced next week. Why push your luck?) But the Metzlers I had on before them scored 12,000 miles, before I had them replaced.

Aside from both of these brands producing great tires, the trick is to keep them properly inflated. And since they are tubless, I carry the stuff to repair a puncture with me all the time.

Fondest regards,
Twisted Roads

"Joker" said...

Sorry I'm so late but I've had buko stuff going on lately.

I personally love these sort of posts. Anyone can say you should do this, or you shouldn't do that. You should buy this instead of that, etc. Only a few people can actually articulate why, and I'm always very interested in why. As you say, your ass is on the line out there and your tires are the first line of defense. I check mine once a week and I love your advice about increasing pressure due to extra weight. I always did that on my truck when I used to plow. With 850# hanging off the front and about 500# of sand in the bed, uh, yeah...those tires need to be pumped up. I used to get a kick out of the guys who'd say it's better to run lower pressure for "traction." LOL!

Speaking of tires, since my Springer only has just over 1K on the factory Dunlops I'm not really worried about them right now. But, when the time does come I've heard much ado about either Avons or Metzlers being a better choice. As you would expect, I've also heard arguments against them because they're "not designed specifically for H-D motorcycles like the Duns are."

I'd be really interested if you'd consider doing a post on this and telling us the facts that backup why or why not to use a different brand of tire on a Harley than the Dunlops. Sorry to create more work for you!