Tire growth

Mike Gray · 09-28-2022, 05:19 PM

I just came from the paint shop and I should be getting color soon. I was going over the final prep and primer and fender clearance issue came up. On my '67 mustang I have about 3/4" between the Hoosier tires and the front of the rear fenders. The tires are 9x29 DO6 on a 10" rim and car should run mid 120's in the quarter.
About how much growth could I expect out of the tire rim combo? I sure would hate to rub the new paint

Run to Rund · 09-28-2022, 06:17 PM

I recommend getting another inch of clearance to accommodate tire growth at speed.

Rory McNeil · 09-28-2022, 11:19 PM

On my 69 & 70 Mustangs, the tight spot was at the front of the wheel opening, mainly from the rocker panel to about 1/2 way up. Personally, I would like more clearance than you currently have, but if you will be running a radial slick, they tend to grow much less than a bias slick.

Mike Gray · 09-29-2022, 01:49 AM

It’s been 15yr since I raced in super street and super gas, but I thought my ladder bar car ran down the track with a little more separation in the wheel wells than it had at rest. I didn’t worry about tire growth because I had plenty of room. Does a Cal-Trac rear lift the back of the car any? I really don’t want to cut the wheel wells on a fastback.
This is what I currently have with no motor in the car.

GTX JOHN · 10-02-2022, 01:59 AM

My Caltracs lift the rear end very little if at all.
With a Radial you would be probably OK. but
as i recall the DO tires is a bias and I think
you will have an issue!

SGSST109E · 10-02-2022, 06:40 AM

On a launch the tire will bunch up in the front.

Mike Gray · 10-02-2022, 11:19 AM

Thanks guys! I think I’m safe on the launch, I checked a bunch of mustang photos by 4284spd and all the Cal-Trac cars separate on the launch. Richie Paulies C/SA looks like it is at least 3” or more. (It may be a result of the mustang rear end mounting. They look a lot like my ladder bar car did)
So now my concern is growth at the top end, I guess I’ll try some test runs when the car is finished and sneak up on the mph keeping an eye out for rubbing. I may have to order some new radials.

427FE · 10-03-2022, 03:10 PM

Not sure if this helps, but i called hoosier on the 18200 that i'll be running and they told me 1"-1.5" max of growth at roughly 130

Run to Rund · 10-03-2022, 03:53 PM

On my car at 120 mph, growth seems like 1+ inch in radius.

Mike Gray · 10-03-2022, 05:17 PM

Thanks for the added info, sounds close but might make it.

09-28-2022, 05:19 PM	#1
Mike Gray Senior Member Join Date: Oct 2006 Posts: 615 Likes: 311 Liked 685 Times in 196 Posts	Tire growth I just came from the paint shop and I should be getting color soon. I was going over the final prep and primer and fender clearance issue came up. On my '67 mustang I have about 3/4" between the Hoosier tires and the front of the rear fenders. The tires are 9x29 DO6 on a 10" rim and car should run mid 120's in the quarter. About how much growth could I expect out of the tire rim combo? I sure would hate to rub the new paint __________________ Mike 7570 A/SA

09-28-2022, 06:17 PM	#2
Run to Rund Senior Member Join Date: Sep 2007 Location: Henderson, NV Posts: 583 Likes: 8 Liked 54 Times in 27 Posts	Re: Tire growth I recommend getting another inch of clearance to accommodate tire growth at speed.

09-28-2022, 11:19 PM	#3
Rory McNeil VIP Member Join Date: Jun 2007 Location: from Vancouver BC Canada, now in Nova Scotia Posts: 1,311 Likes: 317 Liked 1,103 Times in 301 Posts	Re: Tire growth On my 69 & 70 Mustangs, the tight spot was at the front of the wheel opening, mainly from the rocker panel to about 1/2 way up. Personally, I would like more clearance than you currently have, but if you will be running a radial slick, they tend to grow much less than a bias slick. __________________ NHRA 6390 STK M/S 85 Mustang

09-29-2022, 01:49 AM	#4
Mike Gray Senior Member Join Date: Oct 2006 Posts: 615 Likes: 311 Liked 685 Times in 196 Posts	Re: Tire growth It’s been 15yr since I raced in super street and super gas, but I thought my ladder bar car ran down the track with a little more separation in the wheel wells than it had at rest. I didn’t worry about tire growth because I had plenty of room. Does a Cal-Trac rear lift the back of the car any? I really don’t want to cut the wheel wells on a fastback. This is what I currently have with no motor in the car. Attached Thumbnails __________________ Mike 7570 A/SA Last edited by Mike Gray; 09-29-2022 at 01:53 AM.

10-02-2022, 01:59 AM	#5
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,733 Likes: 2,799 Liked 2,483 Times in 697 Posts	Re: Tire growth My Caltracs lift the rear end very little if at all. With a Radial you would be probably OK. but as i recall the DO tires is a bias and I think you will have an issue! __________________ John Irving 741 Stock 741 Super Stock

10-02-2022, 06:40 AM	#6
SGSST109E Member Join Date: Jun 2007 Location: NJ Posts: 351 Likes: 62 Liked 126 Times in 61 Posts	Re: Tire growth On a launch the tire will bunch up in the front.

10-02-2022, 11:19 AM	#7
Mike Gray Senior Member Join Date: Oct 2006 Posts: 615 Likes: 311 Liked 685 Times in 196 Posts	Re: Tire growth Thanks guys! I think I’m safe on the launch, I checked a bunch of mustang photos by 4284spd and all the Cal-Trac cars separate on the launch. Richie Paulies C/SA looks like it is at least 3” or more. (It may be a result of the mustang rear end mounting. They look a lot like my ladder bar car did) So now my concern is growth at the top end, I guess I’ll try some test runs when the car is finished and sneak up on the mph keeping an eye out for rubbing. I may have to order some new radials. __________________ Mike 7570 A/SA

10-03-2022, 03:10 PM	#8
427FE Member Join Date: Sep 2016 Location: Monroe Twsp, NJ Posts: 192 Likes: 260 Liked 348 Times in 79 Posts	Re: Tire growth Not sure if this helps, but i called hoosier on the 18200 that i'll be running and they told me 1"-1.5" max of growth at roughly 130

10-03-2022, 03:53 PM	#9
Run to Rund Senior Member Join Date: Sep 2007 Location: Henderson, NV Posts: 583 Likes: 8 Liked 54 Times in 27 Posts	Re: Tire growth On my car at 120 mph, growth seems like 1+ inch in radius.

10-03-2022, 05:17 PM	#10
Mike Gray Senior Member Join Date: Oct 2006 Posts: 615 Likes: 311 Liked 685 Times in 196 Posts	Re: Tire growth Thanks for the added info, sounds close but might make it. __________________ Mike 7570 A/SA