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Is it 185/70/13 or 175/??/13

Jolyon

my 1981 drophead still has the original Goodyear Grand Prix S 185/70 13 spare.



Still standing !

Depends on year/market/model. All the TR8's had 185/70-13 while some of the TR7's (early?/ steel rim?/ whatever) had 175/70-13.
/Odd

my car still had all of the Goodyear grand-prix's when I first had it, but like Phillip the only one left is the spare.

Early Speke cars had 175-70-13's, all Solihull cars had the 185-70-13's
The tire upgrade was one of the improvements made when they switched over to Canley....



Ron.

Ahem! Will the History class now come to order?

The 175-70-13" tires were used on the 1975 & 1976 standard transmission cars. In 1977 the tires were changed to 185-70-13" and continued on to the end of production.

The Automatic transmission cars used the 175-70-13" tires.

It can be argued the larger tires were used to cope with the increase in vehicle weight due to the heavier LT77 and differential assembly.

Mildred Hargis

The original tyres were 175/70/13 rating HR due to the TR7 top speed being 118mph and around the change over to 5 speed boxes the 185/70/13 HR tyres were introduced.

Jim

My thoughts were that it was 175/70x13 for 4-speed and Auto and 185/70x13 for 5-speed.

The 185/70x13 is the tyre of choice on most cars now. Is anyone using 175/70x13s nowadays?

The orginal tyre on UK cars fitted with 185s was the......
"Good Year G800S". Not sure about the 175s or US cars.

1975 FHC
KDU483N

Thanks folks.

I should have thought about 4 speed and 5 speed cars and how that would affect tyres

Jolyon

Jolyon,

The most popular tyres fitted were Goodyear but Dunlop was used, remember this was the sponser on the TR7 V8 rally.

We have 175x70x13s on the 7 as we could not get 185s anywhere when we put the refurbished wheels on the 7,that was two years ago.
We have replaced all the suspension,uprated springs and polybushed all round and the tyres seem to be performing very well.
Cheers
Moe

Jolyon,

According to my genuine 1977 Leyland workshop manual John has it right.

It gives 175 70 13s for 4 speed, & 185 70 13s for 5 speed cars. It also recommends 24, & 28 PSI front/rear in them.

My first 7 [a 5 speed] had 175s on the front, & 185s on the rear. It handled beautifully.

Hasbeen

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by John Wood</i>



The 185/70x13 is the tyre of choice on most cars now. Is anyone using 175/70x13s nowadays?


<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

tell you one thing....there's an incredible the difference in footprint between my 185's and the 205's ....






Ron.

I use 205 13s on the back of the 7, & 215 15s on the back of the 8.

The 7 will still brake these loose, round a corner, if power is applied clumsily, & the 8 takes quite a bit of care to prevent wheel spin from stationary, or if hit with much throttle below about 80KM/50MPH

Phillip, what's your economy like with those carbs?

Hasbeen

thanks hasbeen

Did you have the gurds rolled to fit those wide tyres?

What do you have on the front? The local tyre shop here says that 185/55/15 are an exact swap for my 13" tyres but I would like to go wider without rolling the edges of the guards.

Jolyon

Yes Jolyon, the guards are rolled, front & rear to take the tyres.

I have that Nissan Skyline diff, which is slightly wider, [1/16" from memory], & the wheel offset is to suit. I have had 205s, & 215 on there with no trouble.

Jolyon you may remember the 8 is seriously low, to the silly stage really. It would bottom on the front bump stops very hard some times. If I parked it, after a run, on the grass, it would scorch the grass under the front mufflers, [hot dogs I believe they are called in youth circles]. It did set fire to it a couple of times.

I had 185 55 15s on the front quite happily, but as a poor mans way of raising the ground clearance a little, I fitted 185 60 15s. These are 2" greater diameter, giving an inch extra ground clearance. It could then clear some speed bumps.

I really like these, they reduced the understeer quite a bit. You can still push the front off the road by bad driving, but it's much better.

The problem was these would hit on those across car reinforcing angles, above the tyre, in the top of the wheel arch.

To fix this I had the front springs reset to give an inch higher ride height, & slightly longer Ford Laser rubber bump stops fitted. These bottom earlier, but softer than the urethane stops I had, [Holden I think].

I like the look of the setup, & the bigger bag tyre suits our roads, & the front grip is still better than the 185 55s, [& it doesn't set the grass on fire].

Richard wants to fit 205 55 fronts, which could be a further improvement, but at present I'm not interested in further changes.

Hasbeen