TWT Forums  

 


Go Back   TWT Forums > General Discussion > General

Notices

Reply
Forum Jump
 
Thread Tools Display Modes
Old 05-17-2018, 08:53 AM   #1
copb8
Forum Supporter
 
copb8's Avatar
 
Join Date: Nov 2013
Location: Highland Village (Dallas) TX
Posts: 929
Cracking and Chunking Pirelli MT21 Tires

I just returned from a 1300 mile trip on my KTM 690 Enduro with a set of Pirelli MT21 tires. They were brand new before the trip. One of my riding buddies also had a 690 with MT21's that had 200 miles on them prior to the trip.

We obviously did a fair amount of street riding at 80+ mph but also some pretty aggressive dirt that was rocky and steep. After an inspection half way through we both found that there were chunks missing from many of the center rear knobs and some were missing completely. Also many had cracks on the base of the knob on the leading edge.

From what I've read the MT21 is a very well respected tire and perhaps we're not using it was designed to be used. Does that seem right to y'all? And if it isn't right, what would you recommend as a replacement?
__________________
Bart (Certified Youtube Mechanic)

16 KTM 690 Enduro R
15 KTM 1190 Adventure R
09 KTM 400 XC-W Plated
copb8 is offline   Reply With Quote
Old 05-17-2018, 11:31 AM   #2
focus frenzy
Moderator
 
focus frenzy's Avatar
 
Join Date: Mar 2004
Location: Cleburne
Posts: 12,013
Re: Cracking and Chunking Pirelli MT21 Tires

the 690 is hard on tires (and chains) I am not sure if there is a knobby tire out there that holds up to it without compromises in traction or will last very long.
__________________
.....Leon
80 GS1000G, 83 GS1100E, 2K ZRX1100 (Tyra), 03 SV1000N(phoenix ) 14 CRF250L
focus frenzy is offline   Reply With Quote
Old 05-17-2018, 11:58 AM   #3
Jampad
 
Jampad's Avatar
 
Join Date: Feb 2016
Location: Pottsboro
Posts: 161
Re: Cracking and Chunking Pirelli MT21 Tires

I haven’t had experience with the MT21’s but currently have the stock TKC80 on my 701... Just did a 1200 mile trip up through the OAT and some TAT into Arkansas and they seemed to perform ok.. Lots of pavement as well... Last year I had the Shinko 804/805 on my KLR for a 3000 mile trip up to and along the CDT and really liked those tires. Another guy had those tires on his Tiger 800 (lots of power) in the same trip and he loved the way they performed... I will be replacing my TKCs with the Shinkos soon!


Sent from my iPhone using Tapatalk
__________________
Jamie

2014 KLR650
Jampad is offline   Reply With Quote
Old 05-17-2018, 12:14 PM   #4
JMZ
 
JMZ's Avatar
 
Join Date: Nov 2005
Location: Gonzales , TX
Posts: 6,292
Re: Cracking and Chunking Pirelli MT21 Tires

Doesn't sound right unless they were ran under inflated.
__________________
2012 Tenere

XR650R

2000 KTM 380 EXC PLATED
1977 Honda Trail CT 125
JMZ is online now   Reply With Quote
Old 05-17-2018, 12:42 PM   #5
Tourmeister
Keeper of the Asylum
 
Tourmeister's Avatar
 
Join Date: Feb 2003
Location: Huntsville, Tx.
Posts: 46,381
Re: Cracking and Chunking Pirelli MT21 Tires

I've seen that when riding in really rocky terrain, sharp edged rocks rather than the smooth rounded rocks often seen in creek beds. The simple fact is that rocks are hard on tires. I have had that happen with the D606s and the MT21s. I ran the D606s on my KLR 650. Most of the time there were just cuts and pieces of individual knobs missing. Occasionally, a few knobs had cracks near the base or were just gone. The MT21s are used on my KTM 530 EXC, same thing. I saw a Terra-Flex get chewed up pretty good on a KTM 625 in one day of riding in the Arizona desert near the Gila River. It was brand new at the start of the ride and had maybe 100 miles on it at the end of the ride...

__________________
Scott Friday

Total Forum Supporter Donations For October: $323.43 - Previous Month: $685.11 - Record High: Jan 16 $1539.42 - 128 Current Forum Supporters out of 20679 Users (0.62%)
Support TWT by shopping at Amazon


The number one rule for this forum!
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. Eph 4:29 (NIV)
Think before you post. Leave out the vulgarity, personal attacks and foul language!

Quote:
"However lofty the goals, if the means be depraved, the result must reflect that depravity." - Leonard E. Read

Lies are fragile. They require constant attentiveness to keep them alive. The exposure of a single truth can rip through an ocean of lies, evaporating it instantly. - Brandon Smith

If you want government to intervene domestically, you’re a liberal. If you want government to intervene overseas, you’re a conservative. If you want government to intervene everywhere, you’re a moderate. If you don’t want government to intervene anywhere, you’re an extremist. — Joe Sobran

It is no crime to be ignorant of economics, which is, after all, a specialized discipline and one that most people consider to be a ‘dismal science.' But it is totally irresponsible to have a loud and vociferous opinion on economic subjects while remaining in this state of ignorance. – Murray N. Rothbard

When one possessed of the Truth suffers from a heavy heart he is susceptible to a more dangerous affliction — the craving for power to eradicate error, to cause Truth to triumph by force. - Frank Chodorov

Where politicians flourish, long history has harshly taught us, people and their liberty wither. Where the state is god and the "public interest" worshipped, individual man will be found bleeding upon the altar. - Karl Hess

The accepted wisdom is that without the state, society would collapse into lawlessness and crime. In fact, lawlessness and crime define the very nature of the state and the society organized by it. - Bionic Mosquito

But the myth of the rule of law does more than render the people submissive to state authority; it also turns them into the state's accomplices in the exercise of its power. For people who would ordinarily consider it a great evil to deprive individuals of their rights or oppress politically powerless minority groups will respond with patriotic fervor when these same actions are described as upholding the rule of law. - John Hasnas
Tourmeister is offline   Reply With Quote
Old 05-17-2018, 03:44 PM   #6
Johnf3
 
Join Date: Nov 2007
Location: West Texas
Posts: 1,111
Re: Cracking and Chunking Pirelli MT21 Tires

Terror Flex--Quite possibly the worst knobby currently made for a dirt bike. Wait, I have had time to think about it and it IS by far the worst.

TKC--Great 50/50 tire if you are only doing light dirt. Not a serious dirt tire because of the very flimsy sidewalls but the fronts last a long time. Rears are useless for me and what/how i ride (actually so are the fronts).

MT21: You got 1300 miles out of an MT 21? My best for a front is maybe 800 miles on my 950 Adventure. I have run several and they are my favorite true dirt DOT knobby by a long shot. There are many variables on why yours chunked knobs. Tire pressure, speed, temperature etc. If you were riding 80 mph on road in warm temps at less than 32 psi then of course it will chunk knobs. At the end of the day it is really a 90% dirt tire that is DOT legal. You have to pay to play on those types of tires. Dirt performance vs. longevity. I will take the dirt performance every time.
__________________
2013 KTM 450 SX-F
2006 950 Adventure S
2010 Husaberg FX 450--Stolen 7/29/17

Last edited by Johnf3; 05-17-2018 at 03:45 PM.
Johnf3 is offline   Reply With Quote
Old 05-17-2018, 04:06 PM   #7
Jeepman
 
Jeepman's Avatar
 
Join Date: Oct 2013
Location: Leander
Posts: 290
Re: Cracking and Chunking Pirelli MT21 Tires

I heard something once about breaking in your tires so they don't chunk. Who's got time for that.
Jeepman is offline   Reply With Quote
Old 05-24-2018, 01:49 PM   #8
copb8
Forum Supporter
 
copb8's Avatar
 
Join Date: Nov 2013
Location: Highland Village (Dallas) TX
Posts: 929
Re: Cracking and Chunking Pirelli MT21 Tires

Ok, did all those things. Rode in very rocky areas with sharp edges and rode 80+ in high temperatures at 30psi.

Heard a recommendation to switch to a Metzeler MC 360 in the rear and Dunlop D606 in the front. Any thoughts on this combination?
__________________
Bart (Certified Youtube Mechanic)

16 KTM 690 Enduro R
15 KTM 1190 Adventure R
09 KTM 400 XC-W Plated
copb8 is offline   Reply With Quote
Old 05-24-2018, 02:30 PM   #9
skinny
 
skinny's Avatar
 
Join Date: Jul 2006
Location: Odessa
Posts: 255
Re: Cracking and Chunking Pirelli MT21 Tires

Quote:
Originally Posted by copb8 View Post
Ok, did all those things. Rode in very rocky areas with sharp edges and rode 80+ in high temperatures at 30psi.

Heard a recommendation to switch to a Metzeler MC 360 in the rear and Dunlop D606 in the front. Any thoughts on this combination?
You don't need 30 psi in any tire on a 690 unless you like having your fillings rattled out...
I've had 3 different 690's, all of which came with MT 21's and never had any chunking or cracking.

15 -18 psi in rear

20-22 in front


usually worn out in about 1500 miles of mixed pavement and off road
skinny is online now   Reply With Quote
Old 05-24-2018, 02:41 PM   #10
copb8
Forum Supporter
 
copb8's Avatar
 
Join Date: Nov 2013
Location: Highland Village (Dallas) TX
Posts: 929
Re: Cracking and Chunking Pirelli MT21 Tires

Quote:
Originally Posted by skinny View Post
You don't need 30 psi in any tire on a 690 unless you like having your fillings rattled out...
I've had 3 different 690's, all of which came with MT 21's and never had any chunking or cracking.

15 -18 psi in rear

20-22 in front


usually worn out in about 1500 miles of mixed pavement and off road
I did 30 based on the KTM sticker but you're saying that's not necessary if you're doing a lot of higher speed street miles?
__________________
Bart (Certified Youtube Mechanic)

16 KTM 690 Enduro R
15 KTM 1190 Adventure R
09 KTM 400 XC-W Plated
copb8 is offline   Reply With Quote
Old 05-24-2018, 02:45 PM   #11
ghostrider1964
 
ghostrider1964's Avatar
 
Join Date: Oct 2007
Location: Coryell city
Posts: 3,975
Re: Cracking and Chunking Pirelli MT21 Tires

Quote:
Originally Posted by copb8 View Post
I did 30 based on the KTM sticker but you're saying that's not necessary if you're doing a lot of higher speed street miles?
Only way I would run 30 PSI is if you had it loaded pretty heavy
I run 25psi on XChallenge and I am a big boy
__________________
BMW R1200GS Adventure, R1150 RT, G650 X/Challenge, Husky FE450 in stable now...too many to keep up with gone!!!
"The older I get, the faster I was", Hardy Baker

http://adventureridersoftexas.com
ROLL The Bones 8, October 213-15, 2017 http://www.rollthebonesrally.com/
ghostrider1964 is offline   Reply With Quote
Old 05-24-2018, 03:21 PM   #12
Johnf3
 
Join Date: Nov 2007
Location: West Texas
Posts: 1,111
Re: Cracking and Chunking Pirelli MT21 Tires

My 32 PSI comment was from the perspective of a KTM 950, so not correct for you 690. If I was running 80 mph for extended distance on the 690 I would run a MT21 at the max tire pressure KTM recommends.
__________________
2013 KTM 450 SX-F
2006 950 Adventure S
2010 Husaberg FX 450--Stolen 7/29/17
Johnf3 is offline   Reply With Quote
Old 05-24-2018, 03:24 PM   #13
Meriden
 
Meriden's Avatar
 
Join Date: Jan 2011
Location: At the back of the pack and out of the dust
Posts: 5,327
Re: Cracking and Chunking Pirelli MT21 Tires

Big fan of the MT21s on my XChallenge. I've worn out several sets including some hard off road in Big Bend and California. I've never had a set chunk. My guess is that they were either old when you bought them or the inflation was wrong. I run 20lbs in mine unless I forget to check, then I may run them as low as single digits. There is no telling how long they sat in the warehouse before selling.
__________________
Meriden

Y'all go ahead. I'll catch up to you at the crash site.
Avatar: Jawbone Canyon Store by Rman
Meriden is offline   Reply With Quote
Old 05-24-2018, 06:15 PM   #14
skinny
 
skinny's Avatar
 
Join Date: Jul 2006
Location: Odessa
Posts: 255
Re: Cracking and Chunking Pirelli MT21 Tires

Quote:
Originally Posted by copb8 View Post
I did 30 based on the KTM sticker but you're saying that's not necessary if you're doing a lot of higher speed street miles?
30 psi for nothing but pavement would probably help extend the mileage,
but for off-road, especially in rocks, the carcass has no flex so the knobs get ripped off or chunked.


For the weight of a 690, at 30 psi it must ride like the tires are full of concrete...
skinny is online now   Reply With Quote
Old 06-04-2018, 07:32 AM   #15
copb8
Forum Supporter
 
copb8's Avatar
 
Join Date: Nov 2013
Location: Highland Village (Dallas) TX
Posts: 929
Re: Cracking and Chunking Pirelli MT21 Tires

As a follow, I mounted another MT21 tire and will run it at 22 psi and see what it does. My friend with an identical bike and who had the same issues as I did on the trip is mounting a Metzeler (can't recall which one) on the back and we'll see how they compare.
__________________
Bart (Certified Youtube Mechanic)

16 KTM 690 Enduro R
15 KTM 1190 Adventure R
09 KTM 400 XC-W Plated
copb8 is offline   Reply With Quote
Reply

Bookmarks

Tags
cracks, ktm 690, mt21


Go Back   TWT Forums > General Discussion > General

Notices


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 07:53 AM.


Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
All Rights Reserved, Scott Friday 2003-12.
vB Ad Management by =RedTyger=
Page generated in 0.21118 seconds with 12 queries