Topic: Help - ideal tire combination for a 1978 CB750 K7

[hakon-cb750]

Hi. What is your idea of ​​the ideal tire combination for a 1978 CB750 K7?
I've searched around the forum, but I'm still a bit confused. I can buy Dunlop's reasonable cheap in DK, so i am planing to go for GT-501's both front and rear. Is that OK?

The old tires are Continentals




Kind Regards

Jakob

[Skunk Stripe]

As long as the tires match, you should be fine. 130/90-17 rear and 110/90-19 front.
Your tire choice should be based on riding style. Bridgestone spitfires and shinko 712s work well for moderate use and have a decent life.
bridgestone battleax tires are usually good for cornering. Avon tires are really good.

[jaguar]

GT501s are one of the best bias tires for the road, or so ive heard.
if not avons are a good tire

[cb750k7]

http://www.mawonline.com/newsite/tires.htm

Have a look here.
They have bargains sometimes...

[dave500]

the bridgstone battlax bt45 has been around for a long time now,and was a sort of "default" tyre to use for ages on any bike,,the pirrelli sport demon is the same cost more or less but a better tyre,,the spit fire falls into the same old tyre group aswell.,i always found the bt45 tread on the front scalloped alot,on two bikes,,as did my neighbours on an older suzy gsx750.,,now,,for the oil recommendations??

[bollingball]

78 K7 ? 1977 K7 or 1978 K8 Looks like the front has been changed a little brakes fender so wheel may be different size. Check the numbers before ordering tire.

                              Ken

[hakon-cb750]

It is a K7.. ok so 110 and 130 it is ..
I'll spare you for questions about oil! I do have trouble finding the front tires in Europe with the size 110x19. Would it be ok to combine 100 and 130 front and rear? Or is that not a propper match?

http://www.avon-tyres.co.uk/motorbike/cb-750-k7

[Erny]

Hi all,

as I do not want to create new tread, I refresh this one.

Actually the same task - what tires for my CB750 K7?
After some search I stabilize dimensions to:
front: 100/90 R19 57V
rear: 130/90 R17 68V

Now to select brand/model. In fact options are limited by dimensions of tires (especially rear one), for the moment I made this shortlist that is available here in Slovakia or nearby:
- Metzeler Sportec Klassik http://www.metzeler.com/site/com/products/tyres-catalogue/Sportec-klassik.html?version=1182270
- Metzeler Lasertec http://www.metzeler.com/site/com/products/tyres-catalogue/Lasertec.html?version=1182270
- Bridgestone Battlax BT45 http://www.bridgestone.co.uk/motorcycle-tyres/battlax/bt-45/
- Continental ContiGo Allround https://www.continental-tires.com/motorcycle/tires/motorcycle-tires/allround/contigo---allround
- Michelin Pilot Activ http://moto.michelin.com/DC/en/tyres/products/pilot-activ.html
- Avon Roadrider http://www.avon-tyres.co.uk/motorcycle/roadrider

Small comparison - overview attached

Can someone recommend or share it's own pros / cons?

I like for the moment Metzeler Sportec Klassik the most (by the design)

And there is second dilema about tube in modern TL tire - as CB rims are TT, can I put tube into moder TL type w/o any issue (I guess so, but I read that tube should not be put into TL tire) - just wonder how you guys manage that?

[seanbarney41]

I would expect any of those to be an excellent choice but I only have personal experience with the Lasertecs and the Avons.  Lasertecs are one of my favorite tires...good grip balanced with acceptable durability.
Avons stick like glue but I sold the bike before I had 1000 miles on the tires.

Might I suggest Pirelli Sport Demons as well?  I have a 130/90/17 on a bike right now also a very sticky tire that I have gotten 6000 miles out of the rear with.  CB750's tend to chew up rear tires pretty fast.

[Erny]

Yes, you are right! I forgot to check Pirelli, those are certaily another good candidate.

So even more difficult to decide

I plan to keep my bike in stock status (has less than 9000 miles only) so classic tread would be plus, but not 100% mandatory.
Definitely grip on dry & wet are priority along with cornering capability.

Let's see if someone else will share experience too.

[dave500]

ive run em all on cb500,i liked the 501s and sport demons the same,the bt45 are just that,a battle axe with less precision,good tyre long wearing though but I feel not as nice if you really want to push corners.

[Stev-o]

the bt45 are just that,a battle axe with less precision,good tyre long wearing though but I feel not as nice if you really want to push corners.

Hey Dave...I've had a different experience with BT45's on my K4.  The read is showing substantial wear after 2000 miles.  But the handling is very good, bike is very solid in the twisties.  I run the pressures fairly high at 38...

[Erny]

And what's about tubes? I guess you have original ones inside new tires, right? No issue with that?

I definitely prefer tires that have maximum grip, as I love cornering... Surely I don't expext I can do it as on my previous CBF1000F (SC64) or BMW R1200GS LC but still I do not want to be limited by tires...

[Stev-o]

And what's about tubes? I guess you have original ones inside new tires, right? No issue with that?

I definitely prefer tires that have maximum grip, as I love cornering... Surely I don't expext I can do it as on my previous CBF1000F (SC64) or BMW R1200GS LC but still I do not want to be limited by tires...

I dont use original tubes, I purchase new ones with new tires, no problem.

All the tires you listed are good and will not limit you.

[dave500]

yeah the high pressures might wear faster?

[Stev-o]

yeah the high pressures might wear faster?

Yeah, typically high pressure will wear the center of the tire prematurely, I should reduce the rear tire pressure. Not an issue in the front and rock solid at high speeds which I like.

[TwoTired]

It's a pressure vs weight loading.  You'll probably want higher pressures when taking a passenger, as that will make the tire squat and yield proper contact patch.

But, if you put wide tires on a narrow rim, the higher pressures stiffen the sidewall support and feel better.  That's the reason why oversize tires are non-ideal for the stock bike rims.   You need the higher pressure, but that makes the center tread wear fast, because the contact patch has been reduced in size.  (Which also negates any traction benefit from having an oversize tire.)

Cheers,

[Yamahawk]

Tire pressures can be varied for your riding preference. But there is a way to find out the optimum pressure for each tire. Start with 32psi front and rear, go out for a ride on a normal temp day in the spring or summer, and ride at least 20 miles on your tires. Stop and check the tire pressure. If they are 2-3psi higher (34-35psi i.e.) you have the correct pressure. If it is higher than 34, you want to increase 2psi cold to 34psi and try again.
When it raises just 2-3psi warm, you have correct temps.
Now... If it is still 32psi or less on your initial test, you want to lower your tire pressure to 30psi and test again the same way. Essentially, you want an increase of about 2-3psi after getting your tires warmed up while riding. This includes riding two up, or touring with luggage and gear also, not just solo.  So you may have to test and adjust your tire pressures for each type of riding. This will give you the best grip and the best handling from your particular tire combination.
This also takes into consideration that your tires match the rim sizes, and that you are not over sizing your tires for the width of your rims. There is a danger of rolling your tires on the rims while cornering and that is why you would have to increase tire pressure for the handling to get better, but that's not the right way to do it, as your tires will wear faster, and in the middle, as you have less contact patch. The correct tire for your rims is the best choice and you will have a far superior ride from you motorcycle this way.
Back when I started riding, I thought that 'bigger' was 'better' and would put the largest tire I could cram into my bike's fenders lol... I realize now that even if it looked 'cool' it wasn't the best nor safest thing for me to do. So, take some advice, and get the proper size tires for your rims, no matter what brand you prefer, and then adjust your tire pressures for an increase of 2-3psi warm. You will be glad you did.
Charlie

[dave500]

#$%* you gotta have a very accurate guage if you get that anal about tyre pressures?

[Yamahawk]

Hehe... Dave, its not anal pressure we are measuring. Its tire or 'tyre' pressure and all of my gauges will read 2psi or better, and I purchase a good one to accurately set the tire (tyre) pressure on my motorcycles, Especially for racing. Now, if you want the best grip and wear from your tires (tyres) then you should get an accurate gauge and see what the recommendations are from your tire (tyre) manufacturer. They ALL have recommended pressures, and I'm not talking about the MAX load and psi on the sidewall. ( I don't want to leave out our friends from across the pond, or from down under )
Charlie

[Yamahawk]

Example of a nice gauge would be this one, accurate to .01psi
https://www.ebay.com/itm/Accutire-MS-5511GB-Pro-Racing-Tire-Gauge/382343826119?epid=1622994157&hash=item590577cac7:g:LQEAAOSw63FaALyJ
or this one
https://www.ebay.com/itm/Accutire-MS-5510B-Racing-Tire-Gauge/122383036390?epid=1517856397&hash=item1c7e98efe6:g:8MMAAOSw4CFYuxaR
Charlie

[Erny]

And what's about these tires: Continental TKV11 / TKV12
https://blobs.continental-tires.com/www8/servlet/blob/50058/25ef1fbe9d64aa0c9c3efab9a3013a8e/produktdatenblatt-tkv11-tkv12-data.pdf

Anyone rides them / have experience with?

[Yamahawk]

And what's about these tires: Continental TKV11 / TKV12
https://blobs.continental-tires.com/www8/servlet/blob/50058/25ef1fbe9d64aa0c9c3efab9a3013a8e/produktdatenblatt-tkv11-tkv12-data.pdf

Anyone rides them / have experience with?

Erne,
  Those Continentals look very nice. I remember Hondaman saying something about the early CB750's not liking tires with sipes that are angled to the tire... But, yours being a 1978, you may be ok with them. They are certainly a good tire, I like Continentals.
Charlie

[Erny]

I found some reviews on the net, seems to be good on dry, not so good on wet. But not so sure for reliability of them

I keep searching for other ones, but thezly look good

[Erny]

Hi all,

I refresh this tread

after searching on the web (spent several hours) I'm till not really sure what is proper size of K7 750 tires in today's metric dimensions... As reminder, original ones are: 3.50 H19 (4PR) and 4.50 H17A (4PR).
Searching on the web (spent several hours), I identified:

Front - 100/90 R19 H
Rear - 120/90 R17

Issue is with rear, there is no tire existing on the market (Europe, Slovakia) with 120/90 R17, with classic tread, at least I did not find any here. Was looking something like was Michelin M48E etc.

Only 120/90 R17 I found is Bridgestone BT45, but has modern look.

However there are some 130/90 R17. But crossreference tables seems I can put 130/90 to my rim 2.50x17, but this is max and I'm bit afraid about handling (I wants it the best possible), there are some opinions that wider tire worsten handling (on narrower rim as it is designed)
http://www.hondatwins.net/forums/52-tires-wheels-brakes/26962-wheel-rim-tire-sizing-important-considerations.html


Can you, K7/K8 owners here advice what available tire to use? Would you recommend 130/90?

Here I have another issue, I need to register bike as historical vehicle and I might be challenged why I used 130 tire...that's why I prefer 120.