TR4/4A TR4 tyres

[Heaney]

Good evening everybody, I wonder if I can get some help and advice regarding some new tyres.
I am restoring a 1964 TR4 and i have just bought five painted 5" wire wheels from Dayton through Roadsterfactory
Question now is which tyres to buy to put on them.
My research so far is leading me towards Vredestein sprint classics - 175/70HR15
As I am replacing 4.5" wheels with 5" I want to try and get this right first time
Also the wheels I have chosen are "tubeless" which i assume means simply that they have a kind of weather strip around the top of the spoke ends
should I put some tubes in anyway? or am I being over cautious ?
I'd really appreciate the benefit of your experience and advice on this .
Thanks and best regards all around
Dawn Labelle

 

[Geo Hahn]

The Vredestein Sprint Classic is a good choice, I have the 165x15 on my stock TR3 rims and the 185x15 on the 5" wide 15" rims on my Jaguar.

Note that those tire sizes are 'metric', in other words, no aspect ratio specified (but it is about 80-82 I think). You may want to look at the tire diameter of the 175/70 and see how that compares with a typical TR4 tire (such as 165x15) -- you probably want it fairly close so the speedometer reads near correct and the tires fill the wheel well nicely.

The Daytons are tubeless as they put some black goo on the ends of the spokes to seal them. A good idea though I had to reseal 3 of the 4 I got from them to eliminate slow leaks - the goo they used looked pretty skimpy to me.

Okay - Here's a Tire Size Calculator you can use to compare the 175/70/15 tires to what a TR4 might have had originally. It doesn't handle metric sizes so perhaps using 165/82/15 will approximate the original size.

By the way - I assume you specifically ordered 5" wheels and are not simply measuring the width of the rims you received. I ask because an original 4½" would indeed measure about 5" across.

 

[TR3driver]

According to my TR4 owner's manual, original bias ply would be 812-813 turns per mile; radials 807-808.

I couldn't find a spec for the Vredesteins in particular, but in general 175/70-15 tires are around 818 tpm, which is very close.

 

[Heaney]

Thanks Geo , Yes I ordered 5" wheels specifically from RF.
would have gone 5.5" for the look but I am concerned about stiff steering at low speed manoevring. Arms like Popeye.
Seems these wheels are on back order!! hope its not too long
Thanks again and to pumpkin

 

[Geo Hahn]

...would have gone 5.5" for the look but I am concerned about stiff steering at low speed manoevring...

FWIW - I run a fairly wide rim on my TR4 and the steering (in my experience) isn't particularly heavier at low speed compared to the 165/15s.

I do not recall the rim width (certainly > 5") but the tire size is 195/65. The ratio on the TR4 steering makes it remarkably easy to steer though having the tires well aired-up probably helps too.

 

[TR3driver]

FWIW, I've got 5.5" rims on my TR3, with 205/55 tires. Low speed steering is OK, I can even parallel park with one hand if I try (tho I usually use two hands). Been driving that way for 20 years or so, and I'm definitely built more like Wimpy than Popeye

If you ignore the sidewall stiffness, then the bottom of the tire has to deform until the area of the contact patch times the pressure in the tire matches the weight on the wheel. So skinny tires give you a long, skinny contact patch, while wide tires give a more round patch. The area is roughly the same, so the force to move it should be similar as well. I didn't notice any big difference in effort between 165, 185, 195 or 205; except the wide tires might have actually been a bit easier! However, I do find that the wide tires handle better with more air pressure, so I'm guessing that's the difference.

 

[Heaney]

Thank you both, that puts my mind at rest a little concerning the wheels and the tyres, I'm going to stick with my order of 72 spoke 5" Dayton wires with Vredestein 175/70HR15's and keep my fingers crossed that i have got it right.
I have another question on this subject. My steering rack is now on my bench to be overhauled but I notice that Moss offers what they call a 'quick rack' high ratio rack that cuts the lock to lock turns down to 2 1/2 from 3 1/2
Anyone out there have experience of this improved system? Once again my concern is that I will make the steering too heavy. If there is any danger of that i will go through my existing rack and replace all the components.
Advice very much appreciated , I want make sure that I can park like the pumpkin with one hand!
Thanks Dawn Labelle

 

[Geo Hahn]

Oh my, I finally worked out the Pumpkin reference. I guess 'cause I've always known him as Randall it didn't register.

I have no experience with the quick ratio but my concern would be the same as yours - increased steering effort.

Perhaps if autocross performance was a priority that would be a desirable feature (as would a higher diff ratio) but for everyday driving it seems to me to be solving a problem I don't have.

 

[TR3driver]

I have absolutely no experience with the TR4 (except the one I cut up for parts). But since the TR3 is less than 2.5 turns lock to lock, and has a more primitive steering mechanism, it seems unlikely that the quick ratio TR4 rack would be all that bad. Still, you can predict it fairly well, 3.5/2.5 says it should take about 40% more effort to turn the wheel. Might be more than you want to risk.

Whether a numerically higher diff ratio is an advantage on an autocross course or not depends a lot on circumstances. With the stock flywheel and the relatively low speed courses found at VTR and Triumphest, I don't think the change would be worth it. You'd just wind up putting more power into the flywheel when launching, and possibly run out of revs on the straight. At any rate, I'd want to look carefully before spending all that money on gears. (Actually, my plan is to go to a 3.45 diff from a Triumph saloon, which will just about compensate for the short tires I run.)

No worries "Yoda", I've been called a lot worse than "Pumpkin"

 

[charleyf]

Randall,
Regarding the 3.45 gears, I have been running them on my cars now for a number of years. I like them a lot. They do give me a couple of miles per hour at the same revs. Of course not nearly what an OD or 5 speed yields. But I find with these high torque engines that getting away from a dead stop lets me stay in the gears a bit longer than with the lower ratio gears. I notice this mostly when following another TR be it a 3,4 or 6. I see them shifting from first to second before they get across the intersection while I can still be in first and easily keeping up with them. The only times they are not helpful is climbing steep hills and following another TR coasting down the back side of the hills. I cannot pace them in the same gear as I tend to overrun them and have to brake to stay behind them.
Charley

 

[TR3driver]

Steve Hedke did some test runs before he ran his TR3 "Scrappy" in The Great Race; and reported that he actually got better acceleration (under the conditions he used) with the 3.45 gears. That was with stock Michelin X tires and a dead stock engine.

Apparently the course instructions for TGR assume infinite acceleration, so it is important to compensate for the actual performance of your car. So if, for example, the instructions say to switch to 40 mph from 30 mph, you have to actually hold slightly over 40 mph for a few seconds to make up the time it took to accelerate from 30 to 40. Steve & his navigator worked out all of the possible pairs of speeds before the race.

 

[Geo Hahn]

I remember when they were practicing for that event. I think they worked out the procedure for coming to a complete stop and getting back up to speed with the necessary actions to end up with the average speed they needed to maintain. As I recall the careful preparation served them well.

 

[TR3driver]

As I recall the careful preparation served them well.

Indeed I believe they took first in their class; and the only thing keeping them from first overall was the bonus points awarded to older cars. Absolutely incredible for their first time out! (On TGR, I mean.)

 

[Heaney]

Hey Yoda, are your Vredestein's 185/HR15 or are they 185/70R15? I checked euro tire as you suggested and they stock both ( I don't really know the difference )
but if you are happy with the tires you have on Dayton 5" 72 spoke rims then I am going to follow suit, easy way out for me the tire size thing has me spinning
Thanks Dawn

 

[Geo Hahn]

I have the 185/HR15s. To be clear, these are on a Jaguar, not a TR. Here's a rear view (not the most flattering but the angle that gives you an idea of the tire's width as mounted:

Here's a side view (though the effect on a TR4 will be slightly different as the full tire is usually visible on a TR wheel well):

FWIW, this is what the sealing looks like that was to make the wheel tubeless. The inner set of spokes were well sealed but the outer had individual dabs of sealant, some of which allowed slow leaks:

Here is the same wheel after I added additional sealant for better coverage (didn't fully demount the tire, just pulled off one side to get at the rim):

Finally, since (so far as I know) the TR4s did not come with 72-spoke wheels here is a shot of my TR4 with 60-spoke wheels. It is a different look as not only the number of spokes is fewer but (I think) the lacing pattern differs:

Those are painted wires and are 4.5" rims with 165/15s but may give you some notion of how a 60 spoke would appear.