Fitted a new Kumho Ecsta AST to the rear, what pressure is recommended?

[sgerksinwi]

Just put this on my spyder.
Went with it because the dealer will do car tires of they are the exact size.
I know there are other options that are better BUT not the exact size.
Next time with all the threads that pertains changing it will be done by me.
Now the question...
After alot of searching here the Tire pressure seems to all over the place .
So what would the recommendation be for it?

[Cobwebs]

Now you've done it! hidesbehindsofa.gif

[CopperSpyder]

18 psi all 3 will get you started. and go down from there, to your liking.

[BLUEKNIGHT911]

I personally use 17 PSI in the rear ... I ride aggressively in the twistie's and do so often. So I just leave it at that .... however you can ride safely on Auto tires down to 15 psi..... This will give a very comfortable ride ..... Mike

[Redbeard]

I'm on my second Kumho Ecsta AST. The first one I ran at 18 psi and got about 14k miles out of it. A month or so ago I put my second on one and am running it at 14.5 p.s.i. and am hoping to get better milage out of it. Just watch how the tread wears and adjust your pressure as needed. At 18 p.s.i. it wore out the center of the tread and usually ride only one up which suggests to high a pressure for the load.

[BLUEKNIGHT911]

I'm on my second Kumho Ecsta AST. The first one I ran at 18 psi and got about 14k miles out of it. A month or so ago I put my second on one and am running it at 14.5 p.s.i. and am hoping to get better milage out of it. Just watch how the tread wears and adjust your pressure as needed. At 18 p.s.i. it wore out the center of the tread and usually ride only one up which suggests to high a pressure for the load.

I'm surprised at this ..... most Auto tires wear fairly evenly at that psi. .... Another member here just reported He currently has 25,000 mi. on the new RIKEN tire ( a tire I discovered and recommend - especially if money is tight ) ..... Mike

[Peter Aawen]

I'm surprised at this ..... most Auto tires wear fairly evenly at that psi. .... Another member here just reported He currently has 25,000 mi. on the new RIKEN tire ( a tire I discovered and recommend - especially if money is tight ) ..... Mike

It's not all that surprising to see this 'centre of the tread' wear start to develop in just about any tire as the tire ages and the tread compounds get compressed thru use and harden thru age/exposure/heat & cold cycles, especially on lighter vehicles like ours. They ALL do it to some extent, but it's seen even more than usual in the more 'performance oriented' Kumho's, as they (often... generally... well, sometimes anyway, depending on which actual tire spec it is! ) have different layers/strips of compound materials in & across the tread compound & face to improve the tires' traction abilities and tread longevity throughout its life in a way that few other manufacturers do! These layers/strips give the tires better traction at lower temps/higher pressures initially, but then as the tire tread gets compressed, hardens, & wears down over time, the operator needs to modify (lower ) the pressure in the tire to better suit the changes that are developing in the compound in order to maintain the traction and avoid wearing out the centre of the tread quicker than is really necessary.

So seeing a Kumho tire that started out running at something close to the 'right' pressure for the load/temp etc it was exposed to when it was first fitted, giving great traction and pretty good tread wear characteristics for maybe 10-15,000 miles or so, then starting to wear the centre of the tread and drop off in traction isn't all that uncommon, especially if the operator 'sets and forgets' &/or fails to review their tire pressure as things change over time. However, it's not something that can't be avoided, as this occurs because the tread layers have been compressed or 'packed down' thru use as well as hardened and worn as the tire aged, so that they're now effectively a harder compound tire than they were initially; so as time/wear progresses, the tread needs to get hotter to work at its best, and that means that the tire doesn't need quite so much air pressure in it any more - in fact, as the operator you NEED to marginally drop the pressure you're running in order to maintain the tires' ability to work at its best for you!

Failing to keep an eye on your tire pressures & tread wear so that you can respond to those changes appropriately means that you'll very likely end up wearing the centre of the tread quicker than you really need to as the tire ages, and it's also one of the reasons you'll see some who haven't done this complain that their Kumho's didn't grip so well in the wet as they got older Yep, it's true - just like any other tire that's being run at too high a pressure, they certainly won't grip so well, especially in the wet; but that's only because the user/operator didn't actively monitor their tire wear & pressure &/or respond to the signs that the tire was beginning to need marginally lower pressure in order to maintain the tire's initial traction levels and to avoid that abnormal 'centre of tread' wear pattern!

Which all adds up to being just another reason to regularly check or monitor your tire pressures, AND to regularly inspect each tire itself for signs of abnormal or changing tread wear! These things we call tires are the ONLY things on our vehicles that should be contacting the ground, and they're one of, if not THE most significant part of the braking, steering, and safety systems on any of our vehicles, so you really should keep an eye on them, look after them, & watch for any changes that might suggest you need to do something sooner rather than later! Kumho tires are pretty good quality tires that WILL perform very well and wear evenly across the tread face for their entire life, IF you do the right thing by them, check their pressures regularly; inspect them often; and check/adjust them as necessary/appropriately whenever it's called for! If they aren't working well for you or wearing/lasting as long as you expected, then there's a very good chance that you haven't been looking after them!

Just Sayin'

Ps: I don't have any current or ongoing business relationship with Kumho Tires, nor do I currently run Kumho Tires on any of my vehicles, but that's only because I got a better deal elsewhere when I purchased the tires I'm running now. However, I have run them in the past; got much better milage than most here report from them despite the extreme traction demands, high temperatures, and outright abuse they were subject to; and I wouldn't hesitate to run Kumho's again on my Spyder, or any of my other vehicles for that matter. But I would keep an eye on their tread wear & tire pressures in order to get the best ride, traction, and tread life from them that I could.

[Cobwebs]

Would a chalk test be of any use in establishing a starting point, and ongoing adjustments for that matter?

[hypurone]

I'm surprised at this ..... most Auto tires wear fairly evenly at that psi. .... Another member here just reported He currently has 25,000 mi. on the new RIKEN tire ( a tire I discovered and recommend - especially if money is tight ) ..... Mike

You have to remember that every tire out there will get circumferential growth at speed... This inherently makes the center wear on a "lighter" vehicle... I run 14psi cold on mine and it warms to 16.5 running and I am STILL getting more center wear on my Yoko...

[Peter Aawen]

Would a chalk test be of any use in establishing a starting point, and ongoing adjustments for that matter?

Chalk test; water mark; the 4psi Rule; anything that gets the operator actively involved and regularly checking will help, even fitting a TPMS like FOBO will help, especially for those who can't get down there so readily to check manually anymore. But all/any of these methods are only useful SO LONG AS THEY AND THE TIRES THEMSELVES ARE CHECKED REGULARLY!

There's no point in having a TPMS on your vehicle if you never check what it's telling you, &/or you never bother to even eyeball the tires let alone visually check the tread & sidewalls for any obvious signs of damage &/or abnormal wear! Sure, you might get away with not doing it for years, or maybe not... cos not checking your tires means you're not checking the ONLY POINT OF CONTACT there is between you and the road - so it doesn't pay to be complacent!

You have to remember that every tire out there will get circumferential growth at speed... This inherently makes the center wear on a "lighter" vehicle... I run 14psi cold on mine and it warms to 16.5 running and I am STILL getting more center wear on my Yoko...

True dat! You really WANT that increase in pressure between your 'cold start' pressure and the pressure after an hour or so of driving/riding, or your tires aren't heating up to their ideal operating temperatures and so won't be working for you as well as they could be; AND you'll be increasing the rate of tread wear, making your traction worse than it needs to be, and a bunch more things besides. There's a bunch of 'Laws of Physics' that come into play here, one of them being Boyle's Law, but all of them basically mean that as the air inside your tire heats up thru use (thereby also heating the tread molecules) your tire pressure will increase. If it doesn't, you've got a leak! And it's the tire designer/manufacturer's task to design/make a tire that will still keep the tread surface in contact with the road as it does all this.

The OEM Kendas REALLY DON'T achieve this aim very well cos they are just too lightly constructed; while the Yoko resists this circumferential growth to a much greater extent. But I suspect your Yoko is more of a performance tire than the Kenda will ever dream of being, and not only does it work better for you in all respects as it is, but ideally, you'd want it to get a little warmer in order for it to work at its best given your riding conditions; only as you mentioned, you've run into the issue of running a tire like that on a very lightweight vehicle! You can't safely run your tire pressure any lower, or you risk popping the bead off the rim (another bunch of Laws of Physics get involved here! ) but the weight of the vehicle isn't enough to keep the tread flat on the road surface nor will it heat the tire up quite enough so that the air pressure inside will help you any more than it already does... But it is also telling you that you've got a little scope there; you could maybe load your Spyder up a bit more; or there's scope to ride it juuust a little harder/faster if possible/you desire?!

[IdahoMtnSpyder]

After alot of searching here the Tire pressure seems to all over the place .
So what would the recommendation be for it?

I laud your optimism! Do you really think you'll get a definitive answer when all the answers you've already seen are all over the place?

[Isopedella]

Pete nailed it with

Chalk test; water mark; the 4psi Rule Check pressures regularly

Or the full novel

; anything that gets the operator actively involved and regularly checking will help, even fitting a TPMS like FOBO will help, especially for those who can't get down there so readily to check manually anymore. But all/any of these methods are only useful SO LONG AS THEY AND THE TIRES THEMSELVES ARE CHECKED REGULARLY!

There's no point in having a TPMS on your vehicle if you never check what it's telling you, &/or you never bother to even eyeball the tires let alone visually check the tread & sidewalls for any obvious signs of damage &/or abnormal wear! Sure, you might get away with not doing it for years, or maybe not... cos not checking your tires means you're not checking the ONLY POINT OF CONTACT there is between you and the road - so it doesn't pay to be complacent!



True dat! You really WANT that increase in pressure between your 'cold start' pressure and the pressure after an hour or so of driving/riding, or your tires aren't heating up to their ideal operating temperatures and so won't be working for you as well as they could be; AND you'll be increasing the rate of tread wear, making your traction worse than it needs to be, and a bunch more things besides. There's a bunch of 'Laws of Physics' that come into play here, one of them being Boyle's Law, but all of them basically mean that as the air inside your tire heats up thru use (thereby also heating the tread molecules) your tire pressure will increase. If it doesn't, you've got a leak! And it's the tire designer/manufacturer's task to design/make a tire that will still keep the tread surface in contact with the road as it does all this.

The OEM Kendas REALLY DON'T achieve this aim very well cos they are just too lightly constructed; while the Yoko resists this circumferential growth to a much greater extent. But I suspect your Yoko is more of a performance tire than the Kenda will ever dream of being, and not only does it work better for you in all respects as it is, but ideally, you'd want it to get a little warmer in order for it to work at its best given your riding conditions; only as you mentioned, you've run into the issue of running a tire like that on a very lightweight vehicle! You can't safely run your tire pressure any lower, or you risk popping the bead off the rim (another bunch of Laws of Physics get involved here! ) but the weight of the vehicle isn't enough to keep the tread flat on the road surface nor will it heat the tire up quite enough so that the air pressure inside will help you any more than it already does... But it is also telling you that you've got a little scope there; you could maybe load your Spyder up a bit more; or there's scope to ride it juuust a little harder/faster if possible/you desire?!

[sgerksinwi]

Definitely will give that a try.
Great idea ��

[mandytuning]

A method we use in sxs world is lay a big cardboard on floor, black paint a portion of the treads and roll the bike over the cardboard to print your treads, try at different air pressures to compare contact patch.

[EdMat]

A method we use in sxs world is lay a big cardboard on floor, black paint a portion of the threads and roll the bike over the cardboard to print your threads, try at different air pressures to compare contact patch.

Great idea. You can also use a wet flat smooth surface, you just have to look quickly.

[sgerksinwi]

They are consistent lower than the post thread's that I look at.
Most of the post are from a quite a few years back.
I quess people are moving to something better.(tire)
I do Iike the chalk idea.

[sgerksinwi]

Another great idea....
Maybe black shoe polish???