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[scottwstevenson]

(I wish I didn't feel morally obligated to make this post, but I think it needs to happen for the safety of others.)

I purchased a Solar E-Clipse at the end of 2024, with 16" Carbon Fiber Wheels.  (I reluctantly sold my Zero DSR, as the E-Clipse gives me a much lighter form factor better suited for when I'll be on the road in the coming months.)

I tied the bike down to my carrier just to haul it around a bit (never tied down overnight - just for a day at a time) to be sure I'd found a safe way to secure the bike with the new carrier, just as I have with the various motorcycles I've been hauling around for 30yr now.

The next time I rode, I noticed an unsafe speed wobble in front tire that never worked its way out, as I had hoped it would. It seems the (front) tire had been deformed.

In a long a convoluted email exchange with Solar in trying to get a replacement tire, it turns out the tires my bike shipped with CST Brand "Scout" tire that were spec'd as:

100/90-16 33B  (Same tire front and back.)

Solar had no replacement tires in stock, but eventually told me I should replace with 110/80-16 55S tires.

There's no problem with the tire dimension (XXX/YY-ZZ) differences here, but the load indices and Speed Ratings noted thereafter are problematic as far as I can tell:

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I believe load index and speed ratings are essentially universal (at least for motorcycles and automobiles), suggesting that the "B" speed rating of the tires I received (for a bike that can go >60mph) shouldn't be ridden faster than 31mph.   (The "S" rating suggested as a replacement totally makes sense, as it indicates 112mph per the Tables below)

Here's a .pdf from CST (manufacturer) with their speed ratings (p. 28) - see attached pic. https://www.csttires.com/int/files/2019/05/CST_PCR2019_Catalog_web.pdf#:~:text=Example:%2086H.%20The%20load%20index%20represents%20the,carry%20at%20the%20tire's%20maximum%20inflation%20pressure.

This table matches what I find several other places online:

https://www.motorcycle.com/rider-safety/motorcycle-tires-101-91339.html

Out of Japan:  https://japan.webike.net/moto_news/webike-original/columns/20200305-simple-and-easy-tips-how-to-read-and-understand-tire-sizes/

https://www.santaanawheel.com/tire-load-index-and-speed-rating/ 

New Zealand: https://www.michelin.co.nz/motorbike/advice-motorbike/tyre-basics/motorcycle-tyre-speed-rating-and-load-rating

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Solar last emailed me over a week ago, as they said they were checking in with CST on this matter. (Solar Support suggested in email that CST has a different rating system for motorcycles and/or specifically for carbon fiber wheels, which I think is unlikely.)   Solar has not provided me an update as to when I could buy replacement tires from them, but I've already installed new ones myself (Heidenau brand, which seems very solid).  There is a WORLD of difference in terms of tire weight, stiffness, ride quality and the speed wobble is now gone of course.

I've now heard from three people who have the same tires installed on their bikes (16" carbon fiber wheels) as mine came with, but I'm still hoping it's only a small minority of purchasers.

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My Questions:

1.) I'm wrong a lot, but I unfortunately suspect that's not case this time.    Am I missing something here as far as the issue with these tires?

2.) I personally am good to go with new tires and the extra expense.  It's totally worth it for my safety.  However, Solar is removing my posts in a message thread on Facebook and not responding appropriately in email.  (This is not the first time.) The Reddit thread I started isn't getting much traction. 

How would you go about dealing with  this situation?...  My main concern is the safety of those potentially affected, which could be a sizable number of people. (The last person I heard from on Reddit just asked what would happen if he were driving along a 68mph and the front tire blew out...)  I'm hoping that posting here will get the word out if I am indeed correct on this issue.  (I would love to have to eat my words and know that I'm wrong - it would make my life easier... LOL)

Best case scenario is folks know they can get a better ride with a tire upgrade.  There are multiple scenarios that are much worse...

(Thanks for reading!)

-S

[TheRan]

Yeah I'm pretty sure you're right, I looked at a few motorcycle manufacturers sites and they're using the same rating system. One even specifically called B tyres moped tyres (or what most countries would call scooters), which makes sense given the 16" size and many 50cc ones in the EU being limited to 28mph/45km/h. That load rating of 33 could also be cutting it a bit close for some people as that corresponds to 115kg per tyre or 230kg combined. I didn't see a detailed spec sheet on their site but if the 60kg bike without carbon wheels is using the same tyres then that leaves 170kg for the rider all geared up or 374 pounds, I know not many people are that heavy but it's possible. And if you're thinking of doing a lot of wheelies and putting all that load on the rear wheel then you better be under 55kg (120 pounds).

[scottwstevenson]

Yeah I'm pretty sure you're right, I looked at a few motorcycle manufacturers sites and they're using the same rating system. One even specifically called B tyres moped tyres (or what most countries would call scooters), which makes sense given the 16" size and many 50cc ones in the EU being limited to 28mph/45km/h. That load rating of 33 could also be cutting it a bit close for some people as that corresponds to 115kg per tyre or 230kg combined. I didn't see a detailed spec sheet on their site but if the 60kg bike without carbon wheels is using the same tyres then that leaves 170kg for the rider all geared up or 374 pounds, I know not many people are that heavy but it's possible. And if you're thinking of doing a lot of wheelies and putting all that load on the rear wheel then you better be under 55kg (120 pounds).

Thanks for the reply and calculations!

Yes, the CST tire-literally says "E-Moped Style" on it, which I would suspect would have helped prevent any unintentional mix-up when putting tires on before shipping out (e.g., if there were some other similar looking CST Scout tires rated differently).

I've tried to be as gracious as possible with regard to the load index, as I've seen a "max weight" listing of 150kg for the E-clipse, so with that stimulation, this tire would technically have that covered, although I would think it would make sense to have a bit more wiggle room.    But add in what this bike is meant to do (vs. a typically street bound "moped"), and it's iffy, but not as black and white as the speed rating. 

(I defer to informed opinions, but I suspect that the load index and speed ratings would / should(?) be determined in an interdependent fashion, given that both speed and weight being carried both will affect the forces the tire has to contend with.)

Thanks again!

-S