Kumho Ecsta AST

[TXWZAZ]

I’m new at this.. What model Kumho or Altimax rear tire do spyder riders run, and roughly how many miles are you able to get per tire? (Is there a reason for having a 225/60/15 vs 225/50/15? Does it affect the bike at all?) I have roughly 8000 miles on my OEM rear tire and it’s already bald in the middle. Not exactly what I expected. I would like to upgrade to something that I get more miles to the tread. Any suggestions?

[triplethreat]

I’m new at this.. What model Kumho or Altimax rear tire do spyder riders run, and roughly how many miles are you able to get per tire? (Is there a reason for having a 225/60/15 vs 225/50/15? Does it affect the bike at all?) I have roughly 8000 miles on my OEM rear tire and it’s already bald in the middle. Not exactly what I expected. I would like to upgrade to something that I get more miles to the tread. Any suggestions?

Bald in the middle of a tire indicates over-inflation. Any tire that is over-inflated will not give longevity and the "normal" amount of miles that a properly inflated tire will yield. It also adversely affects handling and braking performance.

[Dennis in Lodi]

Bald in the middle of a tire indicates over-inflation. Any tire that is over-inflated will not give longevity and the "normal" amount of miles that a properly inflated tire will yield. It also adversely affects handling and braking performance.

Sorry, the exact opposite is also true. Under inflation causes the tire to run hot in the center. Heat gets trapped in the center of the tire and causes the rubber to wear faster. I have 22 psi in my rear tire and 35 psi is recommended. I'm just about down to the wear bars at 14,000 miles on a tire rated for 40,000 miles.

[Peter Aawen]

Bald in the middle of a tire indicates over-inflation. Any tire that is over-inflated will not give longevity and the "normal" amount of miles that a properly inflated tire will yield. It also adversely affects handling and braking performance.

Except when it's a lightly constructed OE spec Kenda, which have thin & light tread plies that simply aren't strong enough to stop the centre of the tread from 'ballooning out' when the tire rotates at just about any useful road speed!!

So while 'bald in the middle of any NORMAL tire' generally indicates over-inflation, it seems that there isn't a safe &/or low enough pressure that'll stop the OE Spec Kendas from rapidly wearing out the middle regardless!! And they rarely last a heap longer than about 10-15,000 miles anyway, but some of us didn't even get 5,000 miles out of their Kendas!! Besides, the rapid centre wear of the Kendas brings with it all those other issues that normally apply, and the Kendas really aren't all that great a tire in ANY handling or performance aspect to start with (except for maybe making your wallet lighter! ) Just about any reasonable quality similar sized auto tire with load & speed ratings that match or exceed those on the Kenda will significantly improve all aspects of your Spyder's tire performance, ride, & handling etc, especially if you run them at a (lower) pressure than that necessary for the lightly constructed Kendas & that you'd usually run in a tire of that same size etc under a much heavier auto - after all, a Spyder weighs significantly less than most autos, and it's the volume of air inside the tire that carries the load! Less load, less volume of air is necessary, or your auto tire fitted to a Spyder WILL be over inflated!

[troop]

Sorry, the exact opposite is also true. Under inflation causes the tire to run hot in the center. Heat gets trapped in the center of the tire and causes the rubber to wear faster. I have 22 psi in my rear tire and 35 psi is recommended. I'm just about down to the wear bars at 14,000 miles on a tire rated for 40,000 miles.

But, you're likely running a car tire versus the OEM spec Kenda ?

[BLUEKNIGHT911]

I’m new at this.. What model Kumho or Altimax rear tire do spyder riders run, and roughly how many miles are you able to get per tire? (Is there a reason for having a 225/60/15 vs 225/50/15? Does it affect the bike at all?) I have roughly 8000 miles on my OEM rear tire and it’s already bald in the middle. Not exactly what I expected. I would like to upgrade to something that I get more miles to the tread. Any suggestions?

Get the Altimax RT43 in 215/60-15 ...... use 18 psi ..... this size will bring your Speedo to just a hair under perfect .... read Peter Aawen's post above - lots of great info ..... Mike .................annnnnnnnd ....

[trikermutha]

Consumer Reports gave the General Altimax RT 43 a "70" for wet traction. CR's rating range is 45-75.

[Dennis in Lodi]

But, you're likely running a car tire versus the OEM spec Kenda ?

I have a Pirelli P4. A 50,000 mile tire and going bald in the center of the tire while the outside looks great. I track straight and true down the road and have been known to spin up the rear tire a bit with the stage 2 flash. But it seems like just yesterday I installed this tire. So over pressure at 22 psi was not the issue for it's wear? And most of the miles I just tool around?
Dennis

[Peter Aawen]

I have a Pirelli P4. A 50,000 mile tire and going bald in the center of the tire while the outside looks great. I track straight and true down the road and have been known to spin up the rear tire a bit with the stage 2 flash. But it seems like just yesterday I installed this tire. So over pressure at 22 psi was not the issue for it's wear? And most of the miles I just tool around?
Dennis

Dennis, what nominal size is your Pirelli? Without knowing that, I suspect that your 'wear in the middle of the tread' problem is only being exacerbated by running a pressure that's too high for the load you & your Spyder place upon that tire, but without knowing the nominal size (just what's printed on the sidewall will do) I can only 'suspect' & don't want to expand on that because if I'm wrong in my suspicions, it might just confuse things...

While you're reading the sidewall, can you take & show us a pic or at least tell us what it says on the sidewall about the tire's Maximum Load & Maximum Pressure?? It's usually a placard that says something like Maximum load xxx pounds at yyy Maximum Pressure. That's possibly where you got the '35 psi recommended' info you mentioned earlier from - except it's probably not that 35 psi is recommended for General Driving, that's usually only meant for when you are imposing the maximum load on the tire..... And if this tire is mounted on the rear of your Spyder, I doubt it's carrying that much load or even near it!! But we'll really only know what these figures are if you tell us what it says on the sidewall.

Over to you.

Ps: those milage ratings &/or tread life estimates on Auto tires are worked out on the basis of the 'average load of an auto' that's likely to be imposed upon those tires as steer tires, and upon the 'average auto power to weight ratio' being delivered thru TWO drive tires.... and while our Spyders do impose a significantly lighter load upon the tires than most autos, they also have a markedly higher power to weight ratio, and then that's put to the ground thru just ONE drive tire!! So while you can use the 'auto derived tread life estimates' as a guide to help you choose your tires, when it comes to their expected life on your Spyder, at best you should only expect at least 1/2 the estimated tread life from them! If you get better than 1/2 /& that estimate (& I'm sure some do... ) then you should consider that you're doing bloody well!

[Dennis in Lodi]

Hi Peter, P215/60, R15. 1477 Lbs @ 44 psi. I run 22 psi, 17,000 kind of hard miles. I want to be more fair on the description. 1st, this specific tire was chosen for it's great grip at controlling excessive wheel spin during the track testing. It was the only tested tire the floated the front end of my RT during take off. I don't recall how many miles the original testing tire had and it might be mute given all the burn outs. This tire is worn across the whole thread pattern but still looks like about half of the outside thread is there. The center is down to the wear bars just like the way the stock tear tire looked at 5,000 miles.
Maybe this is a symptom of the low pressure. Like at the drag strip during a top fuel burn out, the center of the tires expand to be the largest diameter. Maybe more air would hold this great traction tire and not allow the center to expand??
Thanks for passing the time on these slow days.
Dennis

[AeroPilot]

Dennis it sounds like you have your Pirelli about dialed in for your expectations and type of riding. I would say that 17,000 miles isnt bad for what I take to be a "tackier" tire that gives you good performance.

My two cents is that all of our 225/50R15 tires wear more in the middle due to the dynamic bulge of centrifugal force with the light load of less than 600 lbs downforce from bike and rider. The stronger plys from car tire construction help to reduce this as well as I think the 215/60 profile is marginally better, but every tire I have taken off or a picture posted on this site shows greater wear in the center (except for one post by Bajaron on a discontinued tire- I forget the brand) .

I value longer wear so have used the General Altimax and the Kumho Ecsta both with good results, and compromise on pressures usually around 26 psi for the rear. Still wears out a little more in the center but I have got 21,000 miles plus on the 3 Generals and 23,000 miles avg on 4 Kumhos so far on RTs and wifes F3T mostly 1up and running 65 mph for 90% of the 160,000+ Spyder miles on car tires. Just my 2 cents, YMMV

[Peter Aawen]

Hi Peter, P215/60, R15. 1477 Lbs @ 44 psi. I run 22 psi.......
Dennis

OK, sorry about the length of this epic tome to all who aren't really interested in this stuff, but for those who are, here goes!! And I'd like to start by pointing out.....

While using Drag tires can demonstrate some aspects of tire 'growth' pretty well, you need to remember that Drag tires are specifically designed to run quite low pressures (considering their volume) and the design features built into their construction, especially in the area of the treads/plies, actually works to enhance that 'tire growth' for the centre of the tread. The width of the Drag tire at low revs/low pressure/optimal temps provides for massive traction initially, helping to get things moving quickly; then as the revs increase, by design the tire 'grows' in rolling circumference & narrows in width (thereby reducing rolling resistance which can sap power at these extremes) to give better gearing & enable the tire to enhance a rapid transition from delivering 'high traction' to allowing 'higher speeds' down the track.....

So while what you say about Drag tires is true Dennis, in this instance that is more applicable to the OE Spec Kendas than it is to your Pirelli, which is a High Performance Road Tire that's been designed with stiffer sidewalls and a fairly rigid tread section that won't 'balloon out' very much at all. BTW, for those not yet aware, the OE Spec Kendas are very lightly constructed, both in the sidewalls and in the tread area, with far more in common with Drag tires than any 'real' auto/road tire, and their tread DOES balloon out - a LOT! Back to your Pirelli.... as a 'real' auto tire, it starts out with stronger sidewalls and a more stable tread area than the Kendas, which is good for our ride, handling, & tread wear concerns, but looking deeper it gets even better! High levels of on road traction require as much tread surface as possible to remain in contact with the road, both in a straight line and while being subjected to cornering forces, so as a High Performance Road Tire, not only are the Pirelli's compounds specified to enhance traction, but also your Pirelli actually has features built in to its construction that work even harder than most auto tires to significantly limit that 'centre growth' or 'ballooning' that you think is happening! Sure, it does happen to a very small extent (as it does on most tires ) but I'm pretty certain that by design, this is not all that much of a significant contributor to your tire wear in the centre in this case.

However, your tire pressure very well might be contributing at least a little to that centre tread wear - doing a rough calc using the info on the sidewall you gave us, the specs I can readily find for that tire, & using an 'average Spyder load on the rear tire' figure; then all other things being within 'expected parameters', it looks like that 22psi you are running is juust a little on the high side of the optimal pressure for that size Pirelli. The rough calc I did suggests that you should start your 'fine tuning for your optimal pressure' to suit all your ryding conditions and variables at 18 psi, with a lower limit of 16psi (best for traction & ride) and an upper limit of 20psi (which strangely enough, is best for straight line stability & minimal rolling resistance..... ) That said, I'm still thinking there's juust a bit more at play in this particular Spyder Rear Tire wear saga!!

And this is where my 'growing suspicion' comes in. Bearing in mind that the 'nominal sizes' shown on the sidewall of tires are really only 'approximations', most tires vary from those 'nominal sizes' to some degree - some more than others. The OE Spec Kendas are a bit on the 'small' side of their stated 225/50R15, while your 215/60R15 Pirelli is a 'reasonably large' tire for something wearing that size descriptor. From the specs I can find, it seems that while the tread width of the Pirelli is reasonably close to 215mm or about 8.5", the Section Width of the tire is closer to 9"/229mm, and our Spyders run a 7"/178mm wide rear RIM!! While that 7" wide rear rim is still within the 'suitable' range for a 215/8.5" width tire, it is really juuust a little on the narrow side for a 9"/229mm section width tire - so when your 9" section width tire is fitted, the beads are pulled in a little more than is ideal and as a result, the centre of the tread is bowed UP & OUT just a little, creating a slightly raised middle of the tread. And THAT is my 'growing suspicion' as to why some 'otherwise seemingly ideal' tires are still wearing more in the middle of their tread when they shouldn't really!

How to fix it? In your case Dennis, if the tire is otherwise working well and doing everything it needs to for you, maybe you could try lowering its pressure a couple of psi? That might make it 'feel' a little different until you get used to it, but it could also reduce that 'centre of tread' wear at least a bit, and it should improve your traction a little too, even under hard cornering, despite the potential 'feel' changes! Can you put up with/learn to enjoy the changed feel?! Or maybe you could try the same or a similar tire in a 205 width next time? I don't think you'd want to go much higher than a 65 profile tire tho, and you might need to put a tire that size back up to 22psi (if you've tried going lower?) but it should reduce the section width a little and in doing so, minimise any 'bow up' in the tread face which in turn should reduce the wear in the centre of the tread. Worth a shot?

Your call on that, but there you have it... my 'suspicion' about how/why some 'real' auto tires are still wearing in the middle - in this instance, the 215/60R15 Pirelli P4 Dennis is running - it may well be somewhat different for other make/size tires?! Still, before I sign off, it's worth noting that once again, the rough calcs for optimal pressure for this tire also falls within that 16-20 psi range a few of us have been suggesting.... And in closing, as with all this sort of stuff on public forums, you only get a money back guarantee on my free suppositions and surmising; and as always, YMMV, but for what it's worth, there y'are!

[sduskin]

Kumho Ecsta AST KU25 All-Season Tire - 225/50R15 91H

4500 miles on it and it looks unworn.

[Revalden]

Kumho Ecsta AST KU25 All-Season Tire - 225/50R15 91H

4500 miles on it and it looks unworn.

I run this tire also, with 18 psi. Maybe I'll put a camera down there and do some hard cornering to see WTF is happening to the tire while it's working.

[nightcruiser]

your dealer is going to mount it?

[BLUEKNIGHT911]

OK, sorry about the length of this epic tome to all who aren't really interested in this stuff, but for those who are, here goes!! And I'd like to start by pointing out.....

While using Drag tires can demonstrate some aspects of tire 'growth' pretty well, you need to remember that Drag tires are specifically designed to run quite low pressures (considering their volume) and the design features built into their construction, especially in the area of the treads/plies, actually works to enhance that 'tire growth' for the centre of the tread. The width of the Drag tire at low revs/low pressure/optimal temps provides for massive traction initially, helping to get things moving quickly; then as the revs increase, by design the tire 'grows' in rolling circumference & narrows in width (thereby reducing rolling resistance which can sap power at these extremes) to give better gearing & enable the tire to enhance a rapid transition from delivering 'high traction' to allowing 'higher speeds' down the track.....

So while what you say about Drag tires is true Dennis, in this instance that is more applicable to the OE Spec Kendas than it is to your Pirelli, which is a High Performance Road Tire that's been designed with stiffer sidewalls and a fairly rigid tread section that won't 'balloon out' very much at all. BTW, for those not yet aware, the OE Spec Kendas are very lightly constructed, both in the sidewalls and in the tread area, with far more in common with Drag tires than any 'real' auto/road tire, and their tread DOES balloon out - a LOT! Back to your Pirelli.... as a 'real' auto tire, it starts out with stronger sidewalls and a more stable tread area than the Kendas, which is good for our ride, handling, & tread wear concerns, but looking deeper it gets even better! High levels of on road traction require as much tread surface as possible to remain in contact with the road, both in a straight line and while being subjected to cornering forces, so as a High Performance Road Tire, not only are the Pirelli's compounds specified to enhance traction, but also your Pirelli actually has features built in to its construction that work even harder than most auto tires to significantly limit that 'centre growth' or 'ballooning' that you think is happening! Sure, it does happen to a very small extent (as it does on most tires ) but I'm pretty certain that by design, this is not all that much of a significant contributor to your tire wear in the centre in this case.

However, your tire pressure very well might be contributing at least a little to that centre tread wear - doing a rough calc using the info on the sidewall you gave us, the specs I can readily find for that tire, & using an 'average Spyder load on the rear tire' figure; then all other things being within 'expected parameters', it looks like that 22psi you are running is juust a little on the high side of the optimal pressure for that size Pirelli. The rough calc I did suggests that you should start your 'fine tuning for your optimal pressure' to suit all your ryding conditions and variables at 18 psi, with a lower limit of 16psi (best for traction & ride) and an upper limit of 20psi (which strangely enough, is best for straight line stability & minimal rolling resistance..... ) That said, I'm still thinking there's juust a bit more at play in this particular Spyder Rear Tire wear saga!!

And this is where my 'growing suspicion' comes in. Bearing in mind that the 'nominal sizes' shown on the sidewall of tires are really only 'approximations', most tires vary from those 'nominal sizes' to some degree - some more than others. The OE Spec Kendas are a bit on the 'small' side of their stated 225/50R15, while your 215/60R15 Pirelli is a 'reasonably large' tire for something wearing that size descriptor. From the specs I can find, it seems that while the tread width of the Pirelli is reasonably close to 215mm or about 8.5", the Section Width of the tire is closer to 9"/229mm, and our Spyders run a 7"/178mm wide rear RIM!! While that 7" wide rear rim is still within the 'suitable' range for a 215/8.5" width tire, it is really juuust a little on the narrow side for a 9"/229mm section width tire - so when your 9" section width tire is fitted, the beads are pulled in a little more than is ideal and as a result, the centre of the tread is bowed UP & OUT just a little, creating a slightly raised middle of the tread. And THAT is my 'growing suspicion' as to why some 'otherwise seemingly ideal' tires are still wearing more in the middle of their tread when they shouldn't really!

How to fix it? In your case Dennis, if the tire is otherwise working well and doing everything it needs to for you, maybe you could try lowering its pressure a couple of psi? That might make it 'feel' a little different until you get used to it, but it could also reduce that 'centre of tread' wear at least a bit, and it should improve your traction a little too, even under hard cornering, despite the potential 'feel' changes! Can you put up with/learn to enjoy the changed feel?! Or maybe you could try the same or a similar tire in a 205 width next time? I don't think you'd want to go much higher than a 65 profile tire tho, and you might need to put a tire that size back up to 22psi (if you've tried going lower?) but it should reduce the section width a little and in doing so, minimise any 'bow up' in the tread face which in turn should reduce the wear in the centre of the tread. Worth a shot?

Your call on that, but there you have it... my 'suspicion' about how/why some 'real' auto tires are still wearing in the middle - in this instance, the 215/60R15 Pirelli P4 Dennis is running - it may well be somewhat different for other make/size tires?! Still, before I sign off, it's worth noting that once again, the rough calcs for optimal pressure for this tire also falls within that 16-20 psi range a few of us have been suggesting.... And in closing, as with all this sort of stuff on public forums, you only get a money back guarantee on my free suppositions and surmising; and as always, YMMV, but for what it's worth, there y'are!

Dennis I agree with everything that Peter said ..... I have the 4 season version and run it at 17psi ( hard in the twistie's & launches ) .... so far mine is wearing evenly across the tread ...... listen to Peter ..... Mike

[Wildrice]

Ann--Isn't it about time you bought a newer Spyder? It's been over 2 years :-)))

[Dmetcalf]

I have had the Kumho on the rear for 7K and so far I have no issues with wear or traction in any weather. I run 28 psi in it cause I always ride 2 up and it seems to work well for me at that setting. I would purchase another one no problem and my local dealer is ok with mounting it.