Author Topic: Tire pressures for "Classic" spec tires  (Read 959 times)

Offline Scott and Jay

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Tire pressures for "Classic" spec tires
« on: 21.01. 2021 05:22 »
Hi all, I searched the topic in this forum, first. It seems the recommendations about high 20s, front, and low 30s, rear - have been for "modern" spec tires - Avon Speedmasters? I have just been getting Dunlop K70 "replicas". They only cost NZ$175. On the invoice they are called "K70 Classic". I came off my A10 on the 21st November, caught out by a sudden side-gust. Our club repairer is great, he's basically come out of retirement for my insurance job. He said I had been way over-inflating. I said that' what the forums are recommending now for "modern" tires. But he said mine were basically old-spec. It was verified by the wear-pattern. He said it would make it "skittery" which it did seem to be
So, is it that these "classic" tires aren't really modern just because they have been recently manufactured. They still have the "thick walls" like original NOS Dunlops. There are Mitas (Czech) tires on Jay's new A65 acquisition. They were only inflated low by the PO. Looking them up online - they are also called "classic". I have put them (up) to 19 front, 22 rear. I think I will now run my A10 at 21 front, 24 rear. Any comments, thanks..

Online muskrat

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Re: Tire pressures for "Classic" spec tires
« Reply #1 on: 21.01. 2021 07:53 »
G'day S&J.
I've got new TT100's on the plunger with 30 & 32 and find them great but the plunger don't lean like the Cafe with Roadriders at 34 & 36.
At the end of the day it's what your comfortable with for your riding style. Getting it right for you can be scary with the thought of sliding down the road in your mind *eek*
Myself I wouldn' go as low as your planing.
As a side I had a good conversation with a mate about Harley tyres. He uses max pressure of 40/42  *eek*. I know if I did I'd be off in the first corner on mine. 32/34 is good for me.
Cheers
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Online Triton Thrasher

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Re: Tire pressures for "Classic" spec tires
« Reply #2 on: 21.01. 2021 08:38 »
Your club repairer, like everyone else, has opinions.


Online KiwiGF

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Re: Tire pressures for "Classic" spec tires
« Reply #3 on: 21.01. 2021 09:05 »
Yo scott, when i ran dunlop k70’s, not sure if they are the same as your “classic” k70’s, I initially used the book figures, of the period, of around 20psi, then after getting less than 3000 miles out of a rear tyre 🤬  I was advised to use nearer 30psi. This made no difference to tread wear unfortunately 🤬🤬🤬 but seemed a bit safer around corners etc.

I now avoid dunlop tyres due to the incredibly rubbish tread wear, and use “duro” brand tyres, which start with 5/16” deep tread versus the 1/4” of the dunlops, and whilst I have not worn one out yet, these look good (on the rear) for over 6000 miles. I am not a good enough rider to tell if the better wearing compound of the duro tyres results in less grip. I have not worn a front k70 tyre out yet....

I expect to get 12,000 miles from the tyres in my gold wing, which has 115hp and weighs 410kg, go figure. The goldwings tyres (avons) are twice the price of the skinny duros though. It seems the tyre makers (for modern bikes) want you you to replace both tyres at once and the front tyres start with a lot less tread than the rears.
https://www.a7a10.net/forum/index.php?topic=11470.0

Edit: another factor to consider is how the tyre wears and how long one spends with a tyre that has (despite best efforts around corners) worn flat, as that leads to weird handling...for me thats another reason to avoid k70’s as after 2000 miles they have lost their profile and are flat, as you eke thevlast expensive 500 miles or so out of them.
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Online Butch (cb)

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Re: Tire pressures for "Classic" spec tires
« Reply #4 on: 21.01. 2021 09:17 »
I think tyre pressures in days of yore were much less, and I presume due to a stiffer construction and materials back then. Unless these 'classics' are somehow similarly produced then I'd presume they need higher pressures. I'm neither a good or speedy rider and regardless of what I'm on I go with around a low 30 at the front and a mid 30 at the back.
Warning - observations made by this member have a 93% unreliability rating.

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Online groily

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Re: Tire pressures for "Classic" spec tires
« Reply #5 on: 21.01. 2021 09:45 »
Under 3K miles from a TT100 on my A too, now trying a Road Rider at the back with TT100 still up front. K70 rear on a Dommie did even worse - truth in that comment about Dunlops. 
Avon SMs gave me 6K+ comfortably on the rear. Others I've tried include Road Runners some years ago on various machines, and Metzlers and  Pirelli Scorpion (18 incher) on my desert sled. Can't think I've whined about any of them like I have about Dunlops - but nor can I deny that TT100s do handle quite nicely.
Around 30psi for me.
My only 'modern', an XJR Yam which is 21 this year, tends to go 'square' on recommended pressures before all the tread wears off on the rear. About 6K miles on them I think. Massive darn thing, with price to match - using Pirelli Angels at the moment on that, and like them well so far.
Bill

Online Rex

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Re: Tire pressures for "Classic" spec tires
« Reply #6 on: 21.01. 2021 10:05 »
19 front and 22 rear would be dangerously low to me and you must be wallowing all over the road on those pressures.
 I go for 28 front and 30 rear.

Online Black Sheep

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Re: Tire pressures for "Classic" spec tires
« Reply #7 on: 21.01. 2021 10:43 »
I go for about 22 /25. Works for me.
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Online bsa-bill

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Re: Tire pressures for "Classic" spec tires
« Reply #8 on: 21.01. 2021 11:27 »
Quote
I go for 28 front and 30 rear.

I'm with Rex, when I restored my Flash (2000) I set the pressure as BSA spec and didn't like the ride at all, then I read somewhere (possible here) that new versions of the tyres we used back in the day are made differently so while the tread pattern may be the same the carcass construction is not and requires higher pressure
All the best - Bill
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Online RoyC

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Re: Tire pressures for "Classic" spec tires
« Reply #9 on: 21.01. 2021 11:59 »
I put 35psi front and rear, sidecar fitted.
Don't want the tyres slipping round on the rim when accelerating/braking.
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Online JulianS

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Re: Tire pressures for "Classic" spec tires
« Reply #10 on: 21.01. 2021 13:19 »
This from Avon Tyres;

https://www.avontyres.com/en-gb/tyre-care/motorcycle-tyres/

You can see what they say about classic bikes.

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Re: Tire pressures for "Classic" spec tires
« Reply #11 on: 21.01. 2021 15:04 »
Elaborating a bit. Using 30+ psi certainly makes the bikes skittery, especially in the wet, probably because of the reduced contact patch. The same contact patch reduction accelerates wear on the centre of the tread - especially noticable on TT100s, which in my experience were great for racing but I wouldn't use on the road. All that tread reaching up to the sidewalls that you can never use. I find for both plunger and S/A BSAs that the old fashioned looking but modern rubber Avon Speedmaster / SM MkII combination is as good as any.
The Star Twin is currently on trials tyres and the roadholding is still good - you can touch down the centre stand on the left and footrest on the right but the handling is rather interesting.   
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Online RDfella

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Re: Tire pressures for "Classic" spec tires
« Reply #12 on: 21.01. 2021 15:17 »
Well, the tyre manufacturers can specify what they like. I have several classics and most wear speedmaster on the front, K70 on the rear. Lately I've been moving to Avon roadrunner universal on the rear. On most bikes I run around 20psi front and rear (slightly less on rigids for the rear). Tried this 30psi nonsense and it's dangerous. The tyre compound may have changed, but no appreciable change in the construction (walls etc) and nor should there be. Bit like when radial tyres came out - some cars, designed around crossply tyres, were positively dangerous when shod with radials. My (modern) Honda runs 36 / 42 but that's radials on completely different platform.
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Re: Tire pressures for "Classic" spec tires
« Reply #13 on: 21.01. 2021 16:29 »
being a slimish dwarf at 5ft 8inch and 11stone I run 20  front 24 rear solo and  24 front 30 rear with passenger , with French made TT100's. most times I forget to drop the pressure when riding solo again and can tell the difference when hitting uneven road on corners it gets a bit skippy. the mention of these wearing in the middle and expense of replacements would bother me if I was doing 3000 miles a year but I don't, BUT I have seen good reports on some other tyres on this forum and might venture to another make this summer.

Online Triton Thrasher

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Re: Tire pressures for "Classic" spec tires
« Reply #14 on: 21.01. 2021 16:44 »
I get good results using manufacturers’ recent recommendations.