Tire size question

[Mike T]

I own a '06 R1200RT. Last year I put on a set of Dunlap Roadsmarts on my bike. I always run 40 psi in the front and 42 psi in the rear and check them regularly. I just got back from a trip and noticed that the front tire needs to be replaced with less than 5K miles. The tire is majorly squared off with cuppling and the the tread is down to the wear marks. The rear tire still looks fine and should have 2 or 3K miles left on it. I'm in the process of ordering a new tire and noticed that the shop that installed the tires put on the wrong size in front. They installed a 120/60 ZR17 instead of a 120/70. Would this have caused the premature tire wear?

 

I'm about to try a different brand based on the poor showing of the Dunlaps but now wonder if it's more of a size issue? I guess that size does matter.

 

I now install my own tires so this mistake won't happen again.

 

Thanks for the feedback.

[jaytee]

I have always had bad cupping on front motorcycle tires by Dunlop to the point I will not buy their tires any more.

 

I doubt size made that much difference as I have changed motorcycle tire sizes on the front on other bikes and never had a wear problem unless it was fender clearance related.

 

JT

[eej1]

My roadsmart front also wore out before the rear. At 7,000 miles it was toast, it was squared off and the shoulders were worn out, while the rear still had some tread left and looked pretty good.

[JJZorro]

My last set of tires were Conti Road Attacks. Replaced both at 11000 km with the front slightly more worn than the rear. Trying a set of Roadsmarts now and at 3000 km I am so far quite pleased.

[10ovr]

Cant beat PR2's

[jaytee]

Cant beat PR2's

 

for a sport touring tire +1

[Paul In Australia]

I have tried all of them ( except Conti's ) on the Rt's

Bridgestone, Dunlop( rubbish), PR2's and Z6 as well as Pirelli Diablo Strada

 

Beyond all doubt the best for my bike on my roads riding how I ride is the Pirelli's Diablo Strada's. Best by a country mile. third set now and they stick like glue , great in the wet and heat up quickly. Perfect.

best regards

PCH

[RTme2]

I just got done pulling my Pirelli Diablo Strada front tire off the R1100RT at 9060 miles. (Trying a Roadsmart next) I'm very pleased with the Diablo -- still had a nice profile.

 

FWIW...the Roadsmart that is already on the rear is still nicely shaped at 6271 miles with some wear left.

 

Dave

[der Wanderer]

With respect to the question of the OP...

 

Yes, size doeth matter

 

There will be at least 3 consequences in putting the wrong size tire:

 

- Load rating of the tire will be reduced (in your case); that means risk of failure in extreme usage cases

 

- Cornering stiffness will be altered and as a result balance front to rear can be upset (one tire having to give all it has to keep up with the other), leading to at best abnormal wear on one of the tires. Same situation can occur in "mix and match" situations.

 

- Rolling radius will be changed (in your case for a smaller rolling radius), which will have some weird and occasionally unforeseen consequences. The front suspension may be working out of its normal range. And the brakes (ABS and F/R linkage) may be unbalanced, here too leading to uneven braking and wear.

 

If it was on the rear, other obvious consequences would be inappropriate speedometer and potentially overstressed transmission...

 

Altogether that is a real mistake (or I'd rather think, unprofessional commercial choice) on the part of the guy who put the tire on. I'd seek some reparation. And I'd go to a homogeneous assembly - same tire type front and rear - of the correct size.

[RTme2]

What are PR2's? Is that a Pirelli?

 

Dave

[marcopolo]

What are PR2's? Is that a Pirelli?

 

Dave

 

No; Michelin Pilot Road 2 (just got a new set on my RT an hour ago ).

[Twisties]

What are PR2's? Is that a Pirelli?

 

Dave

 

LINKY

[RTme2]

Ahh. I should have known.

 

I had a pair of Pilot Road, original flavor, on a few years ago but didn't like the singing at lean angles and cupping was the most severe of any tires I have had on the bike.

 

Is this a pretty good improvement over the originals?

 

Dave

[marcopolo]

I had a pair of Pilot Road, original flavor, on a few years ago but didn't like the singing at lean angles and cupping was the most severe of any tires I have had on the bike.

 

Is this a pretty good improvement over the originals?

 

Dave

 

I think so. I've had better mileage (on the one set I had on until yesterday), less noise from the front when leaned over and less squaring off of the rear on long-distance rides. As the saying goes, YMMV.

[SWB]

We install all of our own tires now too, which a couple of years ago I never thought I would say. After a couple of sets, we figured out the "easy" way to get them on and off.

 

I bought my current RT with PR2's on it, and the prior owner said they had 5K miles on them when I purchased the bike at 42.5K. Now it's approaching 48K, which means the PR2's have over 12,000 miles on them - unbelievable. I've never got more than about 6K miles on a set of street tires.

 

I've got a left over Diablo Strada front, so I'll get a matching rear and put those on next time. I had a rear Strada on my RT-P with good performance results, but I only put about 1,000 miles on that tire so I can't speak to the long term.

 

Back to the PR2 - it was starting to become squared off, but then my 21year old Ducati riding son started riding my RT, and has probably put nearly 1800 miles on the RT, and wouldn't ya know, that squaring problem went away and the sides look REAL evenly worn now - wonder how that happened. Needless to say, he's a lot more comfortable in the twisties than I am.

 

We'll see how the Strada's work out - they are definitely cheaper than the PR2's. But if I get 6K out of the Strada's and 13K from a PR2, then I guess the PR2's are worth the price.

 

The new RT handles like no other street bike I've ridden, and I'm not sure how much of that is the suspension (ESA) and how much can be attributed tothe PR2's, so I'm eager to compare the bike's handling with the Stradas. If I didn't already have a new front tire, I'd probably just stick with the PR2's - they are that good.

 

... Scott