Firestone SATs (pressure advice)

Hi,

I have Firestone Super All-Tractions which were inherited on the vehicle. I've been trying to research them initially just to get some info on pressures I should be running them at.

It seems they are quite fondly regarded as an off road tyre but renowned for noise and **** handling on the road. Well my Landy is bloody noisy (but I quite like it like that) and I don't drive fast enough at corners to be worried about their handling. Though I am potentially a bit worried that they may catastrophically fail on the motorway as my S3 cruises quite well at 70mph.

So, initial question: What range of tyre pressures can I run?

Secondly, I am keen to know as much about the tyres beyond pressure as possible.

I have tried to research them myself and not found much reference info for them, but like I said there was plenty of fond forum discussions.

That's a good question. I've got a similar problem as I'm running hankook rto3 and haven't got a clue what pressure to put in them so what I did was to look at max psi on tyre and weight.so in my case it says maximum 35psi at 1000kg.so I worked out what load I was putting on one wheel by dividing 35 by a 1000 which gave me 0.035 and then multiplied that by 625 to give me 21.88.not sure if that's the way to do it but I thought that was a bit low so im trying them at 24. Be interesting to see the thoughts of others and wonder if you try my method how you get on.

24psi??? Ex-squeeze-me...and where did you get 625 from? What is this mythical figure? I have owned a spitfire that weighed more than 625kg if thats what it is....can't see a landy weighing less than a spitty...

I'm not sure what to make of these posts?!

Farrar, your method may be correct but it does need a bit more explanation. Like why are you multiplying by 625 and why have you divided 35 by a thousand? Also, why are you dividing 35 by 1000? If you could elaborate I'd appreciate it. However, I would still have the problem that I can't decipher such things for my tyres anyway. The only mention of pressure is on the left two wheels of the four which have a tiny 51psi on. I guess this is the maximum inflation pressure? no mention of any other pressures or load information.

Storm99 - If you know Farrar is on the wrong track, perhaps you might also know the right one and be good enough to point me in the right direction old bean?

Thanks.

Have a search for the chalk test.

Water247 said:

I'm not sure what to make of these posts?!

Farrar, your method may be correct but it does need a bit more explanation. Like why are you multiplying by 625 and why have you divided 35 by a thousand? Also, why are you dividing 35 by 1000? If you could elaborate I'd appreciate it. However, I would still have the problem that I can't decipher such things for my tyres anyway. The only mention of pressure is on the left two wheels of the four which have a tiny 51psi on. I guess this is the maximum inflation pressure? no mention of any other pressures or load information.

Storm99 - If you know Farrar is on the wrong track, perhaps you might also know the right one and be good enough to point me in the right direction old bean?

Thanks.

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What i see wrong is have you gone to the home page Firestone and checked the tire pressure for the vehicle
2 low tire pressure will lead to a tire failure by heat build up ,side wall flexing builds heat
3low tire pressure will cause excessive tire wear, the outside edges will
wear quicker
4 low tire pressure will give you squirrely handling side wall flexing to much, causing the weight of the vehicle to move from the center of the wheel.
ie; stand on two feet straight up, now lean 45 degrees to one side feel the off balance.Your car does the same on under inflated tires

the correct pressure for your vehicle should be in the 30-32 range

Water247 said:

I'm not sure what to make of these posts?!

Farrar, your method may be correct but it does need a bit more explanation. Like why are you multiplying by 625 and why have you divided 35 by a thousand? Also, why are you dividing 35 by 1000? If you could elaborate I'd appreciate it. However, I would still have the problem that I can't decipher such things for my tyres anyway. The only mention of pressure is on the left two wheels of the four which have a tiny 51psi on. I guess this is the maximum inflation pressure? no mention of any other pressures or load information.

Storm99 - If you know Farrar is on the wrong track, perhaps you might also know the right one and be good enough to point me in the right direction old bean?

Thanks.

Click to expand...

I didn't say it was correct and 625 is the dry weight roughly on each wheel.my tyres in small writing say 35psi maximum at a 1000kg so 1kg would be 0.035psi and then I just multiplied that by my load on each wheel.I'm still experimenting myself.I rang up numerous tyre retailers and the pressure varied so much that I thought I'd try something different.oh I'm assuming my land rover weighs 2400kg and then allowed an extra 100kg.still may not be 100% accurate but again if no one knows the ideal pressures I needed to start somewhere.I was running at 28psi before and I'm convinced the ride is better at a lower pressure.may go lower yet.be nice if someone new a proper way of doing the pressures.

Farrar - Ah ha, now I follow your logic and I agree that is what I would have done as well (if I could only have found the right figures on my tyres - not that I know, I am completely guessing hence asking for help here). The weight of my S3 88" is 2120KG. So for the sake of simplifying the maths in your example I'll use 2000KG. So divided by four would mean that each wheel is under 500KG. So if the load on the tyre is half the load used for the maximum pressure figure then is it as simple as halving the max pressure figure? This would mean max psi of 17.5 psi which seems very low, even adjusting the maths to account for a ton of extra weight still only ups this figure to mid 20's. I am not convinced what we are doing is right, though it seems difficult to get any advice or find hard and fast rules anywhere to tell us otherwise!

THE CHALK TEST - Thanks for this pointer it seems to be more what we're after! So for convenience this is what I found in the search:
- Find a nice piece of smooth, level tarmac
- Draw some broad chalk lines across the tread surface of your tyres
- Drive forward about 100 foot (straight line) then look at the chalk marks
- If they've worn away more in the middle of the tyre than on the outside the pressure is too high
- If they've worn away more on the outside than in the middle the pressure is too low
- If they've worn away evenly over the width of the tyre your pressure is spot on

Other threads seem to be suggesting 28 front, 38 rear but don't see how this generic rule can apply with everyone on different tyres with different weights. I will try the chalk test without prejudice and see what pressures that results in.

So the 51PSI on my tyre walls is no doubt maximum inflation pressure, but how do I know what weight that is rated for? Are the figures always for 1000KG or could it be for something different? Presuming they are standardised figures for 1000KG my tyre pressures after the chalk test should fall somewhere in the 25-32.5 PSI range.

It seems to me that to really be conscientious I should be running benchmark pressures whilst the vehicle is empty and inflating to the upper end of the range as I load it up! Do people out there go to these lengths or do they generally try to compromise with a single pressure figure?

I forgot to ask one other thing: These tyres are marked as "regroovable". I have no experience with these sorts of tyres. Presumably getting them regrooved should be done when the tread is wearing down to get additional life from the tyre? And of course that will be cheaper than having to replace them right (what is the approx cost of regrooving and how much would new replacements be for my Firestone SATs 750-16C?)? Do some people retread to get greater tread depth for certain terrains also or is it done purely to increase their useful life when they're worn down?

Thanks as always.

I did the chalk test not easy with mud terrian tyres and my defender sits perfectly at 26psi all round... thought this was a bit low to be honest... but seems ok... any more pressure in and it seems to wear the outside egde out faster than the rest..

Didnt know you could still get re-grovable tyres, i know they do it on lorrys or used to... once it wears out you can re-pattern the tyre using a heat gun...

Water247 said:

I forgot to ask one other thing: These tyres are marked as "regroovable". I have no experience with these sorts of tyres. Presumably getting them regrooved should be done when the tread is wearing down to get additional life from the tyre? And of course that will be cheaper than having to replace them right (what is the approx cost of regrooving and how much would new replacements be for my Firestone SATs 750-16C?)? Do some people retread to get greater tread depth for certain terrains also or is it done purely to increase their useful life when they're worn down?

Thanks as always.

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Do these tires look like tractor tires? Looked on Firestone site and they showed tractor tires 20 psi and 25 mph max speed is this what you have?

john winsemius said:

Do these tires look like tractor tires? Looked on Firestone site and they showed tractor tires 20 psi and 25 mph max speed is this what you have?

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I hope he doesnt :doh:

Not sure if all tyres are given a maximum tyre pressure per 1000kg but if yours were max 51psi that would give you a figure of 25.5psi on your weight.I've added an extra 4psi on mine.when I was running at 28 and 30 it bounced a lot more down the road.I've read about tyres getting to hot and it said if you run for an hour and the pressure raises by more than 4psi they are not inflated enough as they are generating heat.chalk test is ok and tried that myself but where is there a really flat bit of tarmac.mine definitely feels a better ride but I'm still experimenting.wouldn't it be easy if there was a simple answer.

SATS genuine ones are fantastic offroad tyres the Simex of their day in fact I still use them.

On road in the wet forget them they are rubbish I wouldn't want to be doing any more than 50mph on them. Try stopping in the wet at motorway speeds and judge for yourself. The extra time taken to stop is awful. They are up there with worn XCL's for handling! Also they will not last too long on road. Damn good all rounder tyres off road tho

john winsemius said:

Do these tires look like tractor tires? Looked on Firestone site and they showed tractor tires 20 psi and 25 mph max speed is this what you have?

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No they're not tractor tyres. I have done a pretty competent search for technical info on these tyres and come up with sod all and Firestones actual site was as useless as anything else out there! Hence I thought I'd start making some noise here until I got noticed

offroad low speed anything from 8psi up. I used to run them at 28psi on the road and lower them when at comps. Wear rate is high tho they are a better more aggressive pattern and original version of the super mud plugga

Water247 said:

No they're not tractor tyres. I have done a pretty competent search for technical info on these tyres and come up with sod all and Firestones actual site was as useless as anything else out there! Hence I thought I'd start making some noise here until I got noticed

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I used your info firestone sat's came up tractor tire size to fit a defender. so don't bitch at me

as in the outter edges are deep! The pattern is very similar to super mud plugga

jai_landrover said:

SATS genuine ones are fantastic offroad tyres the Simex of their day in fact I still use them.

On road in the wet forget them they are rubbish I wouldn't want to be doing any more than 50mph on them. Try stopping in the wet at motorway speeds and judge for yourself. The extra time taken to stop is awful. They are up there with worn XCL's for handling! Also they will not last too long on road. Damn good all rounder tyres off road tho

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This is nice to hear.. I have been using mine every day and for long motorway journeys at 70mph. I just put the **** stopping down to the car in general and never thought to blame the tyres. It's not been much of an issue as I've just adjusted my driving to leave a lot of space in front of me and I can live with that. Now you've raised the point though I'm sure I would notice a big difference if I swapped to a more road-centric tyre, not just in stopping but also reduced vibration, noise and increased mpg and handling. I'm sticking with them for now though as I'll be cutting down the road use from now on so I think I'll keep it a bit more geared up for off road and make sure I find the time and place to use it as such!

arn't insa doing a remould of them?

I believe mud plugga's firestone copies were made in Wales up unil recently ?