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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 244
Registered: 7-2015
Posted on Monday, 12 December, 2016 - 20:32:   Edit PostDelete PostView Post/Check IP

Hi All
Does fitting lower profile tyres ie 17" wheels instead of 15" give better mpg?
Cheers
Mike
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 449
Registered: 4-2015
Posted on Monday, 12 December, 2016 - 20:56:   Edit PostDelete PostView Post/Check IP

If you increase the perimeter of the tire (irrespective of the rim size) you will travel a further distance per revolution of the tire. That is a mathematical fact, but whether that changes your fuel economy depends on other inputs. In theory only, it should.
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Alan Ford
Frequent User
Username: herne13

Post Number: 95
Registered: 8-2016
Posted on Monday, 12 December, 2016 - 21:27:   Edit PostDelete PostView Post/Check IP

It probably will change your speedo reading, by how much I have no idea..
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 762
Registered: 4-2016
Posted on Monday, 12 December, 2016 - 21:32:   Edit PostDelete PostView Post/Check IP

Mike
Are you considering putting 17 inch rims and tyres on your car?
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Christian S. Hansen
Grand Master
Username: enquiring_mind

Post Number: 450
Registered: 4-2015
Posted on Monday, 12 December, 2016 - 22:13:   Edit PostDelete PostView Post/Check IP

Alan...
My speedo reading is affected by my right foot! LOL!!
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Alan Ford
Frequent User
Username: herne13

Post Number: 96
Registered: 8-2016
Posted on Monday, 12 December, 2016 - 22:31:   Edit PostDelete PostView Post/Check IP

Hahahaha :-) Christian, I hear you.
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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 245
Registered: 7-2015
Posted on Monday, 12 December, 2016 - 23:41:   Edit PostDelete PostView Post/Check IP

Hi All
I mean keeping the rolling circumference the same but with lower profile tyres.
I've been offered some 16" I was thinking about.
cheers
Mike
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Jeff Young
Prolific User
Username: jeyjey

Post Number: 291
Registered: 10-2010
Posted on Tuesday, 13 December, 2016 - 00:53:   Edit PostDelete PostView Post/Check IP

If the tyres are the same circumference, same width, and same compound, then it won't have any effect on fuel consumption.

A wider tyre will get worse mileage. As will a stickier/softer one.

A shorter sidewall (lower profile) might improve the handling, but at the expense of definitely making the ride harsher.

Cheers,
Jeff.
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Jeff Young
Prolific User
Username: jeyjey

Post Number: 292
Registered: 10-2010
Posted on Tuesday, 13 December, 2016 - 00:54:   Edit PostDelete PostView Post/Check IP

Oh, and a shorter sidewall will increase your chances of wheel and tyre damage from potholes....
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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 246
Registered: 7-2015
Posted on Tuesday, 13 December, 2016 - 01:18:   Edit PostDelete PostView Post/Check IP

Cheers Jeff
I was thinking of less tyre wall flexing you see, and most modern cars have lower profile too.
Don't want a harder ride than my turbo R thanks!not with the satae of the "roads" here in UK.
Cheers
Mike
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1220
Registered: 5-2015
Posted on Tuesday, 13 December, 2016 - 02:08:   Edit PostDelete PostView Post/Check IP

Providing the rolling radius of the tyre is the same then no difference to the mpg.

An easy way to make side walls stiffer is the tyre pressure. I use 32psi all round.

The suggested pressures by RR are known as crash in comfort settings.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 763
Registered: 4-2016
Posted on Tuesday, 13 December, 2016 - 07:19:   Edit PostDelete PostView Post/Check IP

Jeff is spot on.

Low profile tyres = harsh ride.
My wife's car has low profile & it is a shocker, it literally hammers over road objects.
I run 28 in the shadow with standard tyres, and there is no way I would change the ride it produces.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 213
Registered: 11-2015
Posted on Tuesday, 13 December, 2016 - 09:25:   Edit PostDelete PostView Post/Check IP

Michael,

Here's some stiff sidewalls.

You can fit larger diameter tires and get better mileage. I first had a set of light truck tires mounted on the RR because that is what I had sitting around the barn for free. While they did lower the cruising rpm, the tires would flex and hit the inside of the rear wheel well on turning.

I liked the look which sort of reminded me of James May's RR Shadow in the top gear India special but hated the ride.

245-75-15's I think.

It's now riding on proper tires.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 764
Registered: 4-2016
Posted on Tuesday, 13 December, 2016 - 10:30:   Edit PostDelete PostView Post/Check IP

Ross,

What brand and size tyres did you fit?
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David Gore
Moderator
Username: david_gore

Post Number: 2348
Registered: 4-2003
Posted on Tuesday, 13 December, 2016 - 17:46:   Edit PostDelete PostView Post/Check IP

Low-profile tyres are notorious for getting damaged sidewalls from rough roads and potholes especially if pressures are not kept on the high side to minimise sidewall bulging.
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michael vass
Prolific User
Username: mikebentleyturbo2

Post Number: 247
Registered: 7-2015
Posted on Tuesday, 13 December, 2016 - 20:50:   Edit PostDelete PostView Post/Check IP

Hi Ross ,is that your car wow!
What are the suggested pressures them Bob?, I usually run 34psi.
Ok I'll stick to my 15" standards.
Cheers all
Mike
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1221
Registered: 5-2015
Posted on Wednesday, 14 December, 2016 - 00:30:   Edit PostDelete PostView Post/Check IP

I believe the suggested PSI is 28 psi all round.

My Jeep is 30 psi. 28 psi and it wallows 32 psi and it rides like a gun carriage.

I am fussy about tyre psi because of tyre damage caused by heat from under inflated tyres


Dave Gore is bang on about low profile tyres.
Further to that aluminium alloy wheels look good but from there on its all down hill. Run a ally wheel with low profile and a pot hole can easily break the wheel, it a common thing in Dorset fall into a pot hole and the shock goes through the car.

Ally wheels are meant to be lighter than steel wheels but this is seldom the case also remember the tyre weight is the same and a 2 ton has lots of sprung weight in comparison to unsprung weight.

To me its all about the look. many will talk about unsprung weight-- yak-drone-bore, but the only reason for alloys is the look. If one needs less unsprung weight then I would suggest driving slower ( public roads )

Steel has advantages such as price and dents can be knocked out -- done loads over the years. Also wheel trims can be removed for cleaning and should the car be a cheap car then there is a plethora of plastic wheel trims on the market.

On police cars we used the cheapest possible plastic wheel trims because the lads often kerbed the cars. A 1 wheel trim and sorted.
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Jonas TRACHSEL
Prolific User
Username: jonas_trachsel

Post Number: 105
Registered: 2-2005
Posted on Wednesday, 14 December, 2016 - 04:53:   Edit PostDelete PostView Post/Check IP

Those super-econo-bluetech fuel saver models put on the market by the big car companies as a "fig leaf"-model (but nobody buys) use extra narrow, highly inflated tyres to squeeze a few extra miles out of a gallon of gas.
Go in the other direction with tyre width and you get the contrary effect.....
Radial tyres get better gas mileage than crossplies, size for size compared.
Jonas
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 216
Registered: 11-2015
Posted on Wednesday, 14 December, 2016 - 09:53:   Edit PostDelete PostView Post/Check IP

Patrick,

I put goodyear comfortred assurance 215 70? 15's. The assurance tread pattern is particularly quiet

Michael,

That is not my car in any imaginable way. If I was going to buy a good handing car it would be a Lotus, and I have a Lotus and even it doesn't have tires that thin.

I suppose the Lotus gets away with tallish 205 65 14's because it weighs 8 lbs.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 217
Registered: 11-2015
Posted on Wednesday, 14 December, 2016 - 10:08:   Edit PostDelete PostView Post/Check IP

Robert,

I was just going to mention what you said about low pressure and tire heat. Low pressure = sidewall flex = heat = rubber degradation.

Alloy wheels tend to weigh less with all the associated good points but on a RR, how could it possibly matter. The car is 5000lbs so I want as solid of wheels as they make. If they made wheels from 3/16 plate I would buy those!

My favorite reason to hate alloy wheels is when they chrome plate them and it corrodes and peels on the bead and you get bead leaks. Noting beats changing a tire and getting sliced open with a piece of razor sharp exfoliated chrome. Good times, that.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1514
Registered: 5-2012
Posted on Wednesday, 14 December, 2016 - 11:06:   Edit PostDelete PostView Post/Check IP

Hi Ross

Have you any pics of your Lotus. From an earlier reference I gather it's an Elite. Is this true - they are very rare and sought after.

Geoff
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 220
Registered: 11-2015
Posted on Wednesday, 14 December, 2016 - 11:37:   Edit PostDelete PostView Post/Check IP

Mine is not that Elite, Or the other one (there is a new one) It is the only one I could afford. A 76.

It looks like a glorified tr7 sort of thing.

They made a lot of these by lotus standards, but that is still only maybe 1500 or so.

here are some pics of the lotus
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 765
Registered: 4-2016
Posted on Wednesday, 14 December, 2016 - 12:54:   Edit PostDelete PostView Post/Check IP

Oh man,

Ross needs to write a book based on his bad experience's, injuries & the chain of events that led to said injuries.

It would be a hoot!!!!
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Jeff Young
Prolific User
Username: jeyjey

Post Number: 293
Registered: 10-2010
Posted on Wednesday, 14 December, 2016 - 20:04:   Edit PostDelete PostView Post/Check IP

Wow, you did quite a bit of work on that Lotus. I had a couple of Turbo Esprits a long time ago. The carb one was great (lots of snap, crackle and boom), the later fuel injected one not so much (much worse turbo lag, and all the fun sounds gone).

Cheers,
Jeff.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1222
Registered: 5-2015
Posted on Thursday, 15 December, 2016 - 01:10:   Edit PostDelete PostView Post/Check IP

There is 2 normally used tyres for the Shadow 235 and 205.

Narrower tyres have less rolling resistance. -------Plus.

From a accurate steering point of view a tyre should be as narrow as a knife edge. But of course that is not feasible because the contact patch would be minute. So width is necessary just not too much.

I think a lot of tyre choice is made on the "look" not the engineering needs.

Some vehicles such as Series 1 and 2 Land Rovers and Citroen 2CVs look better with skinny wheels and tyres and hold the road with a measure good enough for the intended use of the vehicle.

diameter also plays a part the bigger the rolling radius the larger the contact patch is without compromising the steering too much.

It would be interesting too actually weighing the difference between an alloy and a steel equivalent.


Stabbing oneself with tools and car bits is a hazard of working on car. Blood smeared on car bits is expected and no blood means not trying hard enough.

LOTUS Lots Of Trouble Usually Serious.

I love LOTUS Elans but recommend a MX5 instead. 2000 spuds buys a good MX5 mk1.
Lots of after market bits as well cheap.

A mate is doing an Elan hes fitted a modified used/new chassis. The engine is genuine Lotus he ha resisted the temptation to use a MX5 engine/gearbox.
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Omar M. Shams
Grand Master
Username: omar

Post Number: 948
Registered: 4-2009
Posted on Thursday, 15 December, 2016 - 05:59:   Edit PostDelete PostView Post/Check IP

Dear Ross,
I will confess to a slice injury from a slither of chrome that was like a giant blade which peeled off my 2002 Thunderbird alloy wheels. I will never go near a piece of peeling chrome on a wheel ever again.Even 6 months later i still dont have full feeling of the nerves at the tip of my finger from that injury. 5 stitches and a numb finger tip for 6 months.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 221
Registered: 11-2015
Posted on Thursday, 15 December, 2016 - 10:21:   Edit PostDelete PostView Post/Check IP

Omar,

Everyone learns that lesson once. I never trust chromed aluminum for similar reasons.

Robert,

Very true about not recommending Lotus, people who need advice on car buying probably won't fair well with a classic hand built boutique sports car from Hethel. I do the same thing.


Jeff,

Turbo Esprit S1, nice. I have never had the chance to drive one of those. The closest thing is probably the vw/porsche 914 but I bet the Lotus handles better. The Elite I have handles predictably right up to and beyond the limits of adhesion, the 914 handled predictably right up to the limits of adhesion, then it tried to kill you. It also had wide tires fitted which made it tug this way and that when one tried to drive straight.
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John Beech
Prolific User
Username: jbeech

Post Number: 120
Registered: 10-2016
Posted on Thursday, 15 December, 2016 - 13:39:   Edit PostDelete PostView Post/Check IP

I once had an Elan S3 - for about 3 weeks. Ran like stink, not a bit of trouble, lots of fun. Sold it because I doubled my money. A week later I saw the buyer on the side of the road. He saw me drive by and shook his fist at me. Still don't understand why because he chased me to sell him the car and the condition of sale was as-is, where-is. No regrets but I still have fond memories of how cleanly that car handled. Only one I've had where just thinking what I wanted to do effected a change in the line.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1225
Registered: 5-2015
Posted on Thursday, 15 December, 2016 - 23:37:   Edit PostDelete PostView Post/Check IP

John,
I have an image of an Elan surrounded by steam.

I hate selling cars because I know too much about cars. My jeep for instant I know that Jeeps have week stops all of which my Jeep suffers from but I am a mechanic and get round problems fast with minimum expense. If the new owner is not au fait then their at the mercy of garages and a 100 is nothing to spend on a jeep or any car nowadays. I worry.

I find the best way is to run the vehicle until its dead and worn out then sell it for spares or repair, say 200 depends on things like tyres etc.

I have had my Shadow since 1989 27 years and the Jeep 11 years. Both have plenty of miles left in them. I am 65 years old so I guess the Shadow will out last me and I suspect within the next 5 years the Jeep will become not viable. I am looking for a Volvo 245 EST.

Many years ago I brought an Escort Mk2 1300 for 300 and sold it for 525. The new owner kerb the car and blamed the steering which I reset for free. Then he gets nicked for drunk driving so I brought the car back for 325, and resold for 525 again. this time the new owner didnt insure the car and told the police he was on my trade insurance. He said he thought it was my responsibility to insure cars that I sell. The plod soon put him right on that one. Trouble was that I worked for the Police at the time and questions got asked such as should a plod mechanic be selling cars to the general public?
So I again brought the car back and it made 560 at auction. After that I was carefull with whom I sold cars to and insisted that they listen carefully when I explain stuff. However I treated the sale of the car as 3 different cars and made a profit 3 times but the stress of all the fuss over young car buyers not understanding the car buying process and the legals.

One always remembers the troublesome deals and in this case the Escort was a good little car instant starter and good mechanics
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 225
Registered: 11-2015
Posted on Friday, 23 December, 2016 - 10:46:   Edit PostDelete PostView Post/Check IP

This one,

https://www.youtube.com/watch?v=WJ-6LMcXr7k
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David Towers
Frequent User
Username: xtriple

Post Number: 74
Registered: 6-2010
Posted on Friday, 23 December, 2016 - 21:00:   Edit PostDelete PostView Post/Check IP

So LOTUS ownership goes with RR or B ownership? I had two of the damn things (Eclat and Excel)and the costs made Bentley ownership look cheap! But, when they were on song, what cars! Not outrageously fast but the handling was fantastic. My first one (1976 Eclat with ac and pas, leather all the goodies) was so dreadfully unreliable I ended up buying a Lada estate as well so I had something to rely on to get to work... so I could pay for the repairs to the Lotus.
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 228
Registered: 11-2015
Posted on Saturday, 24 December, 2016 - 12:46:   Edit PostDelete PostView Post/Check IP

David,

I hope you raced them. It would be nice to think that there was a Lotus / Lada estate drag race at some point in history.
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John Beech
Prolific User
Username: jbeech

Post Number: 129
Registered: 10-2016
Posted on Sunday, 25 December, 2016 - 00:00:   Edit PostDelete PostView Post/Check IP

Ross,

I greatly enjoyed the YouTube short regarding Elite development, especially the part about the photography because I'm soon to launch a new product and product-photography is on my mind. I also enjoyed the bit near the end where the deerstalker-topped dean of automotive journalism drove the car on the track while his expressive eyebrows proclaimed unspoken volumes about the experience. Great stuff!

Moreover, I allowed my curiosity to get the better of me and poked around your automotive journal. For example, we are on our third Mercedes estate (Lynn loves these things and I can't break her of the habit) so observing your using yours for hauling bags of coal and tree trimmings, plus the saga of being stuck in a snow bank, was very entertaining. For my part, I keep a large truck for this kind of duty though I recently had her car detailed to remove the grease stains from where she had taken old hydraulic hoses to be build for

Also, we once had a 1966 Ford Falcon, which despite the disparaging sobriquet about Ford = Found On Road Dead and Fix Or Repair Daily, was reliable as an anvil. This car also resulted in my first foray into machining (at the university lab in the mechanical engineering department) where under the watchful eye of the shop foreman he taught me lathe and mill operation resulting in wheel-adapters for fitting a set of Lancia 6-spoke magnesium alloys I had purchased for $50 onto the Falcon, which looked stunning on the car because they set off the dark blue body perfectly.

Another memory of the Falcon was about a year before graduating university when I was doing a brake job in the carport. I had rebuilt the wheel cylinders on the kitchen table (using a cookie pan to protect the surface - drum brakes all around) and while I was outside fitting them onto the axles when I went into the kitchen to assemble the master (I had honed it at the same time as the wheel cylinders using my trusty Black & Decker drill and a set of stones) I found Lynn just snapping the rubber dust cap onto the back and sealing it up. She had watched me do the four cylinders and whilst I was reinstalling them had read the instructions and proceeded to do the master.

At this point in time we had only been married 2-3 years but proving I was wise beyond my years, after planting a kiss on the top of her head by way of thanks, I proceeded to reinstall it to the firewall, fill and bleed the brakes, and set out on a test drive without checking her work. I should perhaps mention Lynn is that rare avis; the woman totally unafraid of getting her hands dirty. Also, she's possessed of uncommon good sense (the sole exception being her yes to my marriage proposal but fortunately, my charm prevailed).

Anyway, the Falcon was her principal means of transportation between Tuscaloosa, where I was finishing my degree as an engineering student, and Jasper, a commute of a little more than an hour each way, where she had secured her first job out of university as a teacher. FYI, her area of study being Special Ed. had led to her getting a position at the auto-mechanics trade school interpreting for the deaf students. Along with having been around me a few years, which had by then resulted in her both observing me work on cars in the driveway (for neighbors and less adept friends) and as a direct consequence learning about wrenches and tools while handing me same because expediency had grown to become a great help for keeping us in groceries, meant she had gained more than a passing familiarity to the art of repairing automobiles.

Subsequently, this knowledge has served her in good stead for passing her pilot's license (the written is a common trip-wire for prospective female pilots and less mechanically-astute males) because there's a considerable portion devoted to things that go suck, squish, bang, and puff. Anyway, Ross, thanks for sharing as it allowed me to birdwalk down memory lane this morning ;>)
My best friend for going on 39 years
- Affectionately dubbed Lynnski by our flight instructor, my gal and best friend for going on 39 years tolerates my automobile habit with good cheer and a ready smile
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ross kowalski
Prolific User
Username: cdfpw

Post Number: 238
Registered: 11-2015
Posted on Friday, 30 December, 2016 - 00:21:   Edit PostDelete PostView Post/Check IP

David,

I trust you are aware of this
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 827
Registered: 4-2016
Posted on Friday, 30 December, 2016 - 09:15:   Edit PostDelete PostView Post/Check IP

That's awesome Ross.

I didn't like Clarkson that much, but the boys certainly came up with some great ideas on their show, and were not afraid to try different things.

Top gear will NEVER be the same.

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