Tire Advice for Stock Steel Wheels

[bikermike]

I am seeking recommendations for replacement tires for my 67.5 SPL311 using the stock steel wheels.

The current rubber has lots of tread left, but from looking at the receipts from previous owners, the tires are vintage 1994 - which is concerning.

Question #1 - Tire Size: The owner's manual states that the original tires were "5.60S14-4PR" which I believe translate to 175/65/14. Currently the car has 185/70/14 tires installed. Would there be advantages / disadvantages with running something wider with a lower profile that is close in circumference to the originals, say 185/60/14 or 195/60/14?

Question #2 - Tire Brand / Model: I'm interested in suggestions on tire brands and models / tread patterns for the Roadster with the stock wheels. Living in the SF Bay Area, I'd be looking at a summer tire and do not intend to drive the car in the rain (intentionally). My driving will be normal street driving will occasional spirited driving on curvy mountain roads.

What has worked for you? Thanks in advance for your suggestions.

-Mike

[pebbles]

Will you run a whitewall?
Stock ride height I like the look of a 185 70, which is 10 mm too wide for the wheel. A 60 just doesn't fill the wheel opening well enough. Andy has 185 75s and I can sure feel the sidewall flex. A 185 65 may give a little more rigidity to the sidewall for the spirited mountain drives. I suppose it all depends on the look and feel that one wants. 175 65? Early z wheels are an inch wider and look nearly the same, but don't have tha hubcap clips.
Inflation pressure variables 22-30 will make a big difference as well.

[bikermike]

The more I think about it, the more I like the idea of a whitewall for that retro look. In combing through this forum and other websites I think the 185/70/14 is the tire size I will stick with. The overall diameter is close to the original tire spec (24.6") and I like way the current tire fills the wheel well. Plus I know that it works.

Looking at current local tire offerings, I think I have only a few choices in whitewalls:

Uniroyal Tiger Paw AWP II
Hankook Mileage Plus II H725
Bridgestone Insignia SE200

Does anyone have any experience with either of these?

I realize that without going to a lower profile tire on a wider 15" wheel I'll probably not get too much improvement in cornering performance, so for the stock wheels I'll find a set of reasonably priced whitewalls as a trade off.

Suggestions are welcome.

-M

[RobertAuclair]

I am running the 185/70/14 on stock rims until my budget allows for the 15in VTO's.

[DatsunBucky]

Question #1 - Tire Size: The owner's manual states that the original tires were "5.60S14-4PR" which I believe translate to 175/65/14.

Actually, 5.60 x 25.4 = 142.24, so the closest "metric" size to the original tires would be a 145/83-14. They were almost unbelievably skinny. And bias ply. "Back in the day", a 70 profile was considered "Wide Oval", at least according to Firestone, who coined the term.

[spl310]

Unless I am mistaken, you can't do a conversion that accurately as the 5.60 was a bias ply which has a taller installed profile than a radial with the same nominal diameter. On the 1500s a 155 80/13 was deemed to be the closest match to stock, so it would stand to reason that on the later cars a 155 80/14 would be close. Now to add a fly to the ointment, a 6.45x14 was an option on the 2000s...

[bikermike]

Thanks for engaging in the discussion guys.

Here is my current thinking...
My revised assessment in a follow up post above was that I'd need a tire with a diameter close to 24.6" to match a 5.60-14. I based that on a spec from a BF Goodrich 5.60-14 bias ply I found online:

http://store.cokertire.com/560-14-bf-go ... n%20false;

The 5.60 in the tire size is not the tread width like on a modern tire. It is the section width. Recall that bias ply tires had a narrow tread and bulge in the sidewall.

That tire has a 4" tread, 5.6" max section width and I believe an 83 aspect ratio (based on an ebay seller's specs).

I couldn't find any details on the orginal Toyo E41P tires from the 60's, but let's assume it matches the BFG.

So to maintain ride height and speedo calibration in a modern tire, I'd be looking at a tire with a diameter close to 24.6" and section height of 5.3".

I read some of the MGB forums (sorry looked at the dark side) since it also was spec-ed with a 5.60-14. No surprise, their forum's tire discussions parallel ours.

So, 185/70/14 has a diameter of 24.2" and a section height of 5.1" (pretty close). I don't want to go wider to a 195 on the 4" stock rim. Going narrower to a 175 yields no tires available in a 75 or 80 aspect ratio. So after all this analysis, I have come to the conclusion to just use the same size that is on there already. It looks like others are having success with it as well, although some sources indicate that the rim is too narrow for the tire. I spoke to a tire guy on the phone and he said I should be ok as long I don't to anything too crazy.

WHEELS:
I have also learned that there are 2 versions of the stock wheel: a 4" and 4.5" version. I looked at the 5 wheels I have for the the car. Four of them have no stampings on them, which I read in the forum archives mean they are 4" wide wheels. The 5th rim has some stampings on it - photos below. I presume the "11-68" is a date code. Since my car is a 67.5 I guess one of the wheels was replaced at some point. The other stamping is shallow. Since it has a "14" in it I suppose it is the size.

-Mike

[pebbles]

I am now curious as to when these 4.5" wheels were introduced, the addition of the big flares, and/or the 2000? Or 68?
I concur that the date stake is just that.

[spl310]

The 4.5" wheels originally were introduced on the 67.5 2000s. Early 67.5 1600s had 4" wheels, later 67.5 1600s had the 4.5" wheels. This is based on my observations. If you really want to nit pick the restored cars, check those date codes on the wheels!

[kenw]

Not a whitewall, but I'm running Yokahama Avid t4's in 175-70-14. LOTS of room between the rear tires and the fenders, with a stock early '67. Definitely could go wider, but that's what was available locally when I needed them. No complaints as far as performance, wear etc goes.
fwiw,

[pebbles]

To correct my earlier post, examining the 4/74 "Z" wheels, the stake mark is 5. So they are 1/2 " wider than the roadster 7/68 4.5" roadster wheel. Back spacing is 3.5" for the 4.5", and 3.75" for the 5".

[bikermike]

I measured the stamped and unstamped versions of my stock Roadster steel wheels yesterday. The good news for me is that they are the same size. Both were 4.5" wide with 3" backspace. The bad news is you can just apply a rule of thumb to assume the width.

[bikermike]

Just updating the thread... I'm going with Hankook Mileage Plus II H725 whitewalls in 185/70/14 for my stock wheels. I'll post pics once I have them on the car.

[bikermike]

The new tires are installed. What a difference in ride and handling compared to the old tires!

The stripe on the tires are 0.75" thick which looks pretty good. I don't know what the original Toyo's were, but it's close enough for me.

I was running 32 psi today. Any suggestions on tire pressure?

[pebbles]

If you were to jump on the freeway and drive 1000 miles at 70 mph, 32 front 30 rear. 50 mph through the mountain windeys, 30 front 28 rear. It's mostly a preference of feel. Every car and driver are different. I've run 28f 26r and really liked it. But my seats are shot!