Why did tyres get so fat?

[A100man]

Stock fitting on the 1988 (95 BHP) FZ750 is 130/80 (although mine sports a slightly wider 140/70).

A current Trident 660 (80 BHP) has a mahoosive 180/55..

why did that happen - can't be just for the look, can it?
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[doggone]

They don't last any longer and the sheer mass of rubber must contribute to higher price.
The contact area with road is probably very slightly more but mostly it's all about looks IMO

[A100man]

[redeem ouzzer]

To be fair the FZ handles like shite as all bikes running skinny crossply tyres do, having an 18" rear isn't ideal either. Hence why most folk resto-modding them fit 1000 Eggcup wheels.

However - I will give you that about the Triumph being "over tyred" - a 160 rear would be more than adequate and might actually aid steering.
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Be a REAL MAN!

[A100man]

[DJP]

Of course it's fashion. And yet journos are moaning that the new Honda Hornet has "Just" 160 section tyres.

It's a 90bhp, 190kg bike FFS. It doesn't need a 180 section tyre.
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Suzuki Bandit 1250
https://deejayp999.atwebpages.com/index.html
That's http not https

[MarJay]

I bet a 180 section tyre is the same price or cheaper than something weird like a 140 section tyre. So many bikes use the 120/180 combo, that tyres are so common and the choice is immense. You can't say that bikes with that combo handle badly because of it, as so many fantastic bikes have that combo.

Don't complain, you could be getting 21" fronts on knobblies and having to have that haul you around a 90mph switchback.... oh wait...
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[xX-Alex-Xx]

[Robby]

Pair deals for common tyres are a lot cheaper than unusual sizes.

[Nobby the Bastard]

But.... rears wear out faster fronts.

I had a front in my garage for 3 years because I bought a pair and then COVID kicked in...
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[to v or not to v]

the bigger the tyre the more you can be charged for it.
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current bike Yamaha Thunderace.
its old and fat, but its a damned good ride. the bikes not bad either.

[rpsmith79]

[Easy-X]

My father-in-law's Harley: front 130/60 21" back...

240/40 18"
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[A100man]

OK, so I get the current economies (of scale) to be had for everyone on 17" wheels, similar sizes etc..

..but the original question still stands - why did they get fat in the first place?
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[redeem ouzzer]

[A100man]

[DJP]

[Robby]

Of course, despite all of the good reasons, the core reason is that fat tyres look good and that helps sales.

Slightly annoying for me, particularly for something I found out after buying my bike. It's a Guzzi V9, with a 150 section rear. Guzzi have been using basically the same frame and shaft drive setup since the 60s, with skinny tyres. For my bike they had to alter the shaft drive to clear the wider tyre, which meant limiting rear wheel travel.

So I have a wide tyre that I don't need, and worse rear suspension.

[MCN]

Big tyres can put more load on the road and carry more weight.

And stuff.
Contact Patch.

Run cooler. (Not overheat and get sick)

Not sure looks are a thing.

Maybe the looks thing is only due to the increased power needing Big fat tyres and therefore a relationship between the two.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[stinkwheel]

It was mostly for the look of it.

The TL1000s was a classic case in point. They fitted a comparatively massive rear tyre to them for the time they were released which was a large part of why they used to get random, unrecoverable tankslappers (there were other issues too mind). If you fitted a slightly narrower tyre, they didn't do it.

It boggles my mind how wide a tyre they fit on even 125s these days. There are guys doing 100mph laps of the IOM on 90/90 fronts and 100/90 rears in the classic racing scene. It's what I have on my 612 enfield, it'll be making 3 to 4 times the power of a 125 and I've never noticed a lack of grip or traction.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[sickpup]

[MarJay]

[sickpup]

[that_impulse_guy]

my 60hp 400 ancient has slightly skinnier tyres than my 12hp 125.

I can "get" tyres for my 400 cheaply, if I dont want a 240kmph speed rating....because tyres in those sizes arent used on 400's anymore but lesser bikes.(and may make me fail MOT and life)

I can "GET" tyres in my sizes and with the desired speed rating, but then i have to spend an armful...compared to the "125" tyres.
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Gone: Yamaha DT50lc, Suzuki DR500, Suzuki A100, Kawasaki z250ltd, RD350YPVS, Suzuki DR Big, Kawasaki AR125, Kawasaki KMX200, Suzuki GS1000S, Katana 1100, GS550M, Suzuki RGV250
Now: Suzuki GSX400X, Suzuki RF900R, NS400R

[Nobby the Bastard]

Why in gods name do you need tyres rated to 150 mph on an old 400?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050