Question: Tire growth on bias ply tires

[NCAmother]

I'm running a set of BT45's.  I was just curious what kind of tire growth can I expect on track days?  I'm running a BT45 130/80/18 rear (I think that's what it is)  Thanks :)

[rocker59]

None.

[rodekyll]

Ummm . . . unless you've got some sort of tire that attracts bits of everyone else's, it's not going to grow.  I think the opposite happens.


   <---  ducking and running

[jacksonracingcomau]

I'm running a set of BT45's.  I was just curious what kind of tire growth can I expect on track days?  I'm running a BT45 130/80/18 rear (I think that's what it is)  Thanks :)

Here we only get 45V in that size
From Bridgestone 663mm OD and 131mm width assuming 3" rim

All tyre manufacturers publish "actual hot" figures on web, the numbers between different makes on same nominal size vary hugely, fitting on wrong rim changes it again.
Measure cold to see any growth difference.

[redrider]

As in getting taller and narrower as speed increases?

[cwiseman]

All I can add is the BT45 is my tire of choice. I'm not concerned with tread life, I want it to stick very well when hot, cold, wet, or whatever. You should be very happy with them, enjoy!

[Sasquatch Jim]

  As in moss grows on the north side of a non rolling tire?

[Yukonica]

If you are using BT45 for track days because that is what you have in hand then burn them off and enjoy. But if you want a stock tire that has much better grip in all conditions: stick on a set of Demons. Been through two rears and one front on the Pirelli and am on the second front and third rear on BT45's. Pirelli is the better tire in my opinion; just doesn't have quite the durability of Bridgestone. But I'm not on a track.
.. and I'm cheap.

[NCAmother]

Here we only get 45V in that size
From Bridgestone 663mm OD and 131mm width assuming 3" rim

All tyre manufacturers publish "actual hot" figures on web, the numbers between different makes on same nominal size vary hugely, fitting on wrong rim changes it again.
Measure cold to see any growth difference.

Thanks, I never new they were measured hot.

[NCAmother]

As in getting taller and narrower as speed increases?

yes :)

[NCAmother]

If you are using BT45 for track days because that is what you have in hand then burn them off and enjoy. But if you want a stock tire that has much better grip in all conditions: stick on a set of Demons. Been through two rears and one front on the Pirelli and am on the second front and third rear on BT45's. Pirelli is the better tire in my opinion; just doesn't have quite the durability of Bridgestone. But I'm not on a track.
.. and I'm cheap.

Yeah,  I was going to use the BT 45's at the track, I have minimal clearance (1/2")

[Yukonica]

Yeah,  I was going to use the BT 45's at the track, I have minimal clearance (1/2")

Minimal clearance? Are you riding a modern V7? Your original post stated tire size capped with 'I think".
"I Think" leaves a great deal of room for speculation: over one half inch worth. Have you changed up the rims?
If not; you are either still on 17" tyres or you have Red Green's affinity for duct tape.
If you are on 17" wheels, you have lots of space for 'expansion'... unless you install nitrous.
Attending track days on a 50 HP bike?: Buy sticky tires and save the body work for a winter project.
"What is learned on the track: stays on the track. Keep the skills ready but the testosterone channeled."

[NCAmother]

Minimal clearance? Are you riding a modern V7? Your original post stated tire size capped with 'I think".
"I Think" leaves a great deal of room for speculation: over one half inch worth. Have you changed up the rims?
If not; you are either still on 17" tyres or you have Red Green's affinity for duct tape.
If you are on 17" wheels, you have lots of space for 'expansion'... unless you install nitrous.
Attending track days on a 50 HP bike?: Buy sticky tires and save the body work for a winter project.
"What is learned on the track: stays on the track. Keep the skills ready but the testosterone channeled."

The frame has been modified and braced, I have 1/2" clearance to one of my gussets.  Yes, I will ride the track on a 50hp bike. I don't know what you are talking about with the duct tape.  I have a BT 130/80/18.

[redrider]

yes :)
I doubt there will be that much given the way the carcass is layered during construction although I have never experienced the event. You might try searching "High speed tire growth photography". I have seen the slow motion top fuel rears balloon up but that is low pressure leaving lots of wiggle room.

[PeteS]

I don't know about tires growing in diameter but have had tires get wider with time. When I was running Dunlop 591s they came very close to to the swingarm when new. After a few thousand miles they would rub on the swingarm. This happened with a couple of sets. My personal favorites for the LeMans were Avon Super Venoms, NLA.

Pete

[charlie b]

Tire 'growth' with speed happens mainly at higher speeds/wheel RPM's.  At the rated speed for the tires they may 'grow' a mm or two.  You really won't notice it as the contact patch is still large compared to the growth.

[Yukonica]

e I will ride the track on a 50hp bike. I don't know what you are talking about with the duct tape.

It was a reference to a TV show where the 'host' fixes everything with duct tape.
You have an 18" rim to mount the 18" tire?... just asking.
Last year a vendor shipped me a 19" front tire for my 18" V7 wheel. You could pass the rim clean through the carcass. They sent me a fresh tire.

[rocker59]

The frame has been modified and braced, I have 1/2" clearance to one of my gussets.  Yes, I will ride the track on a 50hp bike. I don't know what you are talking about with the duct tape.  I have a BT 130/80/18.

 
The tire will have little or no measurable "growth" from heat or speed.

Motorcycle tires are stiff.

[SteveAZ]

The frame has been modified and braced, I have 1/2" clearance to one of my gussets.  Yes, I will ride the track on a 50hp bike. I don't know what you are talking about with the duct tape.  I have a BT 130/80/18.

Hell yeah you can track a 50hp bike. - thumbsup -

(emojis arent working for me right now)

[NCAmother]

It was a reference to a TV show where the 'host' fixes everything with duct tape.
You have an 18" rim to mount the 18" tire?... just asking.
Last year a vendor shipped me a 19" front tire for my 18" V7 wheel. You could pass the rim clean through the carcass. They sent me a fresh tire.

Yeah, 18" rim.  In my head I was going to originally use a 17" rim, but found a set of spoked rims that were 18x3 and 18x2.15. They just happened to be attached to a 1975 Tonti carcass

[Chuck in Indiana]

The tire will have little or no measurable "growth" from heat or speed.

Motorcycle tires are stiff.

This.
Growth?? Seriously? You're worried about a half inch clearance?

[NCAmother]

I'm just really paranoid.  The last thing I want to happen is the tire grab the gusset and something bad happening.

[Groover]

I think the most growth that will happen will be when squeezing the 130 on the 2.15 rim. I noticed that happened when I put the 120/90 on my 2.15, so I'm guessing the same would happen with the 130/80.

I don't think the growth you're thinking of that happens on dragsters would happen much on our tires. The section width just isn't there to allow that sort of flex.

That's what I'm thinking at least.

[NCAmother]

I think the most growth that will happen will be when squeezing the 130 on the 2.15 rim. I noticed that happened when I put the 120/90 on my 2.15, so I'm guessing the same would happen with the 130/80.

I don't think the growth you're thinking of that happens on dragsters would happen much on our tires. The section width just isn't there to allow that sort of flex.

That's what I'm thinking at least.

Thanks Groover, yeah I have more experiences with cars and tire growth and contact patch play an important part.  I have a 3" wide rim, I'm guessing if the tire was on an 2.15 rim it would "squeeze" the tire and make them taller?  Cheers

[Groover]

What's the rim that you are using? Is that a Guzzi rim?

[NCAmother]

Maybe you could help me identify the rim:  It says 18 3  with a sideways anchor (british?) and it's anodized gold.  The gold looks great on the rim, unfortunately the front is stock bare aluminum.

[Groover]

No, sorry. I don't recognize that.