Rear tire (automotive) pressure?

[petegtsv10]

I just installed a Kumho Ecsta on my wife’s F3. I did a lot of searching on this forum regarding suggested tire pressure. I found a variety of different numbers in parts of misc threads and thought we could use this single thread to consolidate many suggestions in one place. This will make things simpler for those doing a search in the future. So, what psi have you found suits you with your car tire on your F3?

 

[JKMSPYDER]

I run 20 psi in my General Altimax rear tire. Smooth ride and even tire wear.

 

[JayBros]

Based on watching SL for more than four years and now on my first auto tire, I would say that unless you find a poster who is exactly the same weight as your wife and who rides exactly like your wife and has a Kumho Ecsta, you or your wife are kind of on your own in determining the optimal tire pressure for her. Your biggest difference I think is the stiffer auto tire sidewalls. I'm still playing with rear tire pressure on my Altimax but began at 28 pounds and have been going down, am now at 26. The one thing I have not done yet is really push the Spyder in the NC mountain twisties, but I suspect if I was going on a ride to do so I'd probably drop to 24. No two Spyder riders ride exactly alike.

 

[AeroPilot]

Wifes 16 F3T has 24 psi cold on her General Altimax .. before that she had 26 psi on the Kumho. She has 40,000 miles currently and only weighs 110. Works for her. The fronts are usually 17 psi or so as it seems to steer and perform well there. Your choice...

 

[BLUEKNIGHT911]

Tire pressure in an Auto tire …………. because Auto tires are almost THREE times as strong as the OEM Kenda, it doesn't need more than ( approx.. ) 18 PSI to work at it's optimum performance...… Think about this - a tire that can support 1300 to 1400 lbs. is not going to be ( realistically ) affected by a load change of even 150 lbs. ………. If you are concerned about a weight change - how many of you increase your CAR or Truck air pressure when you fully add passengers for a trip ???? … I think maybe 10% will do this …….. I ride aggressively in the Twisties and keep my ( rear ) AUTO tire @17 psi. I'm very happy with the way My RT responds...……… good luck ...Happy New Year …. Mike :thumbup:

 

[Beaudog]

The problem with arguing tire pressure is the gauges used. When my tire is 20psi using my gauge it might be 18 or 22 using your gauge. Using a calibrated gauge helps but there are lots of people using gauges that are no where close to correct. I run my altimax at 18 to 20 using a gauge certified +/- 2%. And, just because a gauge is digital does not mean it is more accurate than an analog one.

 

[Road-Kill]

Since you put an untested unrated tire on your Spyder you need to do tests yourself.
1. Load your bike as if you are going to ride it.
2. overinflate your tire and slowly release air until all the tread makes contact. (note the pressure)(you need to eyeball it with your head on the ground)
3. you need to do breaking tests and adjust accordingly.
Many moons ago I added a 4" lift to my Ford Bronco and added monster unrated tires to it.
Since there were no citations, tire ratings and internet at that time this was the method used and it works.

I just installed a Kumho Ecsta on my wife’s F3. I did a lot of searching on this forum regarding suggested tire pressure. I found a variety of different numbers in parts of misc threads and thought we could use this single thread to consolidate many suggestions in one place. This will make things simpler for those doing a search in the future. So, what psi have you found suits you with your car tire on your F3?

 

[wingit3611]

2016 RTL SE5 Kumho Ecsta 225/50-R15 91H @ 25lbs. Still need to go down. Mite just jump down to 20. Vee rubber on front @ 19lbs.

 

[UtahPete]

I run 20 psi in my General Altimax rear tire. Smooth ride and even tire wear.

:agree:

 

[petegtsv10]

The problem with arguing tire pressure is the gauges used. When my tire is 20psi using my gauge it might be 18 or 22 using your gauge. Using a calibrated gauge helps but there are lots of people using gauges that are no where close to correct. I run my altimax at 18 to 20 using a gauge certified +/- 2%. And, just because a gauge is digital does not mean it is more accurate than an analog one.

My gauge is calibrated about once a year. So is my torque wrench.

 

[r1100rider]

I just installed a Kumho Ecsta on my wife’s F3. I did a lot of searching on this forum regarding suggested tire pressure. I found a variety of different numbers in parts of misc threads and thought we could use this single thread to consolidate many suggestions in one place. This will make things simpler for those doing a search in the future. So, what psi have you found suits you with your car tire on your F3?

The way the racers do it is chalk the tire then with the load that will be used roll the bike or car across smooth flat concrete with dark paper and look for even caulking marks to much there will be more in middle to little more on edges and cupping in middle

 

[petegtsv10]

Thanks for the input. I now plan to start at 20 psi and adjust up and/or down from there. I'll base my final decision on handling characteristics, comfort and application of the 4 psi concept. At least now I have a good initial psi.

 

[KX5062]

Thanks for the input. I now plan to start at 20 psi and adjust up and/or down from there. I'll base my final decision on handling characteristics, comfort and application of the 4 psi concept. At least now I have a good initial psi.

Also go for a ride and get the tire fully warmed up and then measure the air pressure using the same gauge. Then compare that figure to the figure you already have from the cold inflation and check for variations between warm and cold numbers, that's a good indication of heat build up.

The air inside of the tire is also used to cool the rubber, so if it's too low heat will build up and cause premature wear. This is an often overlooked concept when discussing tires and air pressures.

 

[Sarge707]

I'm at 21-22 on the New Kumho on F3 200 Pounds- At 24 in the summer it would spin much more than the stock so I lowered it to 21 and in the cool weather 38-50 degrees it seems much better. I'm more careful in cold weather because it doesn't heat up the rubber like summer!

 

[always young]

Reference wingit3611, he mentioned that he is running a Kumho 225/50R15 on his RTL. I'm pretty sure the 2016 F3 has the same swing arm as the RT. The numbers on the Kumho width for the 225/50 seems to be wider then the OEM tire. My question, for you, do you have sufficient clearance to the belt with this size and not have any belt rubbing on the tire? I'm looking to replace my stock tire soon and was looking at the 215/55R15 and I was wondering which size would be a better choice. Thanks, and have a happy New Year everyone!

 

[petegtsv10]

No clearance issues on our F3 with the Kumho.

 

[jaherbst]

My gauge is calibrated about once a year. So is my torque wrench.

You recalibrate your tire gauge once a year? How in the world do you do that?

Jack

 

[jaherbst]

Nothing more exciting than to read about everyones opinion on tire PSI!

Jack

 

[petegtsv10]

[that improves life’s QUOTE=jaherbst;1411986]You recalibrate your tire gauge once a year? How in the world do you do that?

Jack[/QUOTE]
I send it to Accugauge and they calibrate it. Probably not quite as often as once a year, but it’s been done several times. Many cars I’ve owned use ultra expensive tires ( like 355x20 Michelin Pilot SuperSports) and I want to monitor their psi closely. That improves lifespan and optimum handling characteristics.

 

[Road-Kill]

Even more exciting is people who think PSI and traction are the same thing.

Nothing more exciting than to read about everyones opinion on tire PSI!

Jack