The manual calls for 36 psi on the rear tire... How much air can I let out of the rear tire without long term damage or performance loss? I'm looking for a softer ride in the rear. I have my low rider shocks maxed, so no adjustment there...

 

How much can you let out? None IMHO! By doing that you are likely to introduce handling and stability problems. If you are uncomfortable you need better shocks!

 

+1 grbrown

 

Don't mess with your air pressure!

 

If you go down on air pressure you don't gain much rear end softness, and you actually prematurely wear out your tire & lose some handling due to excessive sidewall flexing. In the old days, some people would lower their tire pressure due to hard tailing the bike so the ride wasn't so bone jarring. Too low of air pressure makes the rear end feel all squirrelly. Been there, done that when I found I was down some psi due to a screw in the tire.

 

i have found that below 30psi on my bike the rear gets loose ...and I am a light 155...if you weigh more you need to make the pressure higher....

 

Despite ALL of the advice above, I can assure you (and will put money on it) that you will see performance GAINS from your tires by lowering the pressure. Motorcycle tires are not automobile tires, they need to get hot and soft in order to perform properly. Additionally, they will deform around and in road imperfections, rather than transmitting those incidents onto the responsibility of the shocks, keeping the bike steadier and allowing you to drive it harder. You will find a softer, smoother, better handling ride as a result. Yes, tire wear will be a little more severe. Tires are made to wear out.

36 psi is your manufacturer's recommendation for a fully loaded tire - unless you have a 200 pound passenger with loaded saddle bags, you don't have a fully loaded tire.

Drop the PSI to 30 (cold), ride it. Report back - I'm willing to bet money that you will be pleased. You will probably be even happier at 26-28 (cold).

My sporty rides best at 28 front, 26 rear, cold. I'm 140lbs. My VROD runs best at 22psi cold on that big 240mm rear.

Don't want to take my word on it, fine go to a motorcycle racing forum and ask around about street tire pressures.

 

Messing with tire pressure is a bad idea. Try replacement springs and shocks instead. Keep tire pressure to specs.

 

Please explain how this is a bad idea.

I would make the argument that it is a better, faster, cheaper, and perhaps smarter idea to establish your preferred tire pressures than it is to change springs or shocks. It is very interesting to me how every piece of our bikes are considered fair territory to most tinkerers for performance changes, but tires seem off limits. Tires changes can offer THE single most dramatic performance change on your bike, if done properly. The pressure recommendations from HD and the tire manufacturers are set to be safe for the vast majority of riding conditions, including a fully loaded down bike. No way in hell the same psi for a fully loaded bike is optimal for a lightweight guy on a chopped up bobber, but most riders seem to think the number on the sidewall is the way to go without even considering why.

If you've ever raced anything with big tires, you'd know this. But for car pressures, we usually wind up going higher than the rec - even 50+ psi on tires with 30psi recs, but cars are not motorcycles. Motorcycles need LOWER pressures to perform properly, but very few of recreational users know this.

I was having a lot of trouble with my Sporty and I talked to a professional motorycle racer friend of mine, he laughed at me, told me to drop them down to 25, and go from there. Incredible performance gain! Same thing when I got my vrod, much better performance at lower pressures.

Now - given that it takes only a moment to alter your tire pressures, and great perf changes are possible, how much sense does it make to do something so complicated and difficult to change as shocks and springs without even attempting to see what different tire pressures can do for you?

Just makes no sense to me. Something so easy to do, but we'd rather buy expensive springs and shocks and mess with an ounce or two of shock oil. I really suspect that most shock and spring changes stay put just because it's so complicated and costly to reverse, and you don't have to think about it - there they are - advertised, with instructions, if someone said it's so, it must be.

Lower your tire pressures. You can always change it back, but you won't want to. You can even do this with your child's bicycle pump, don't even need a quarter for the gas station pump.

One final thought - think about this - your tire pressures are always changing, as much as 10 pounds per sq inch even during a single riding session. Plus, they're always leaking air. How many of us check our tires to find they're "5 pounds down" or more - was it unsafe? You didn't even notice, but you probably thought you were just becoming a better rider.

 

Essentially because what you said before ain't right! The purpose of a tyre is to provide some cushioning between wheel and road, but also to provide dependable grip and stability. The recommended pressures are a guide to providing those, although I will agree they are only that. Reducing pressures to significantly lower levels reduces the stability of the tyre and hence the bike, which is likely to become unpredictable and frankly unsafe. Not for me thanks!

The place to improve ride quality is with better quality tyres, better shocks and more comfortable seat, in that order. You should try a set of Ohlins shocks and experience just how magic they are to ride on! With the correct pressures of course!