Wheel clearance favour ..... anyone who's done this?.....

Post by **iambiggles** » Tue Mar 15, 2005 7:50 pm

I'm guessing that those of you with oversize (from standard) wheels have measured the clearance from the front of the wheel mounting to both the arch and the suspension (front)

My mog is off having its headlining done at the mo and I'm just trying to work out what I can get on the front and rear.

I've got a set of wheels from Minor Developments in 14x5. There is a negative(?) offset. I think thats right... if I measure from the back plate of the wheel to the front rim its a bit over 6cm, if I measure to the rear its 10cm. Is this a negative offset? Anyhooo..... Has anybody done that measurement from the face to the suspension?

I'm thinking of putting either a 155/80 or a 165/80 on the front (where the main issue will be) and according to Toyo (who make the tyres i'm looking at) the width of the 155 would be 156mm (less than the rim to rim width), the 165 would be 162mm (slightly more). Now I'm wondering if this is the contact width of the tyre width? According to toyo its the "overall inflated" width.

On the back I'm thinking of a 185/80 and don't think this will be any problem as there's not much for it to hit (183mm width tyre).

So if anyone has this info at hand, could you pop it up here. I could always wait until Friday when I get the car back, but, damnit, I'm impatient ;)

Cheers in advance chaps and chapesses.

Post by **rayofleamington** » Tue Mar 15, 2005 8:15 pm

You can use 165 on the front with the Minor development 5J rims - it should give enough room to put your finger between the tyre and the top trunnion.

Offset is the distance between the wheel rim centre and the mounting face. Negative offset gives a very odd looking wheel!

The 165 tyre will be WIDER than 165mm at its widest point

Post by **iambiggles** » Wed Mar 16, 2005 8:00 am

rayofleamington wrote:You can use 165 on the front with the Minor development 5J rims - it should give enough room to put your finger between the tyre and the top trunnion.

Offset is the distance between the wheel rim centre and the mounting face. Negative offset gives a very odd looking wheel!

The 165 tyre will be WIDER than 165mm at its widest point

Cheers Ray - I'll go with the 165 then as that keeps both front and rear in the same tyre series (330).

What would these wheels be described as then? The wheel is certainly "pulled into" the car by about 1" from the centerline of the rim, so is this a positive offset then? (i.e. mounting face pushed out from the centerline) - not important really, I just like to know this stuff

-- edit... Just googled it... positive it is

Post by **rayofleamington** » Wed Mar 16, 2005 9:14 am

Cheers Ray - I'll go with the 165 then as that keeps both front and rear in the same tyre series (330).

Well 185's should be ok on the rear if you really want, but the advantage of using the same tyres is that you only need 1 spare and also you can swap tyres between front and rear.

Post by **Alec** » Wed Mar 16, 2005 9:23 am

Hello Biggles,

a 5" rim is approximately 125mm, i.e. a lot narrower than even the 155 section tyre, fwiw.

Alec

Post by **rayofleamington** » Wed Mar 16, 2005 9:41 am

i.e. a lot narrower than even the 155 section tyre

Correct - and that is how it should be, as the tyre then protects the rim flange from damage. The tyre istself is shaped to accomodate that, but with a decent size sidewall it can accomodate a bit more.
The outside edges of the rim will be approx 10mm per side wider than the inside edge (making 145mm) and therefore the 155 is ok, and the 165 is fine.

You need to be extra careful when using stupid tyres (eg 245/35 profile) as there is virtually no sidewall so it will not adjust to a smaller rim by as much as a normal profile tyre. Hence making it far easier to damage the rim on kerbs etc...

a 5" rim is approximately 125mm, i.e. a lot narrower than even the 155 section tyre, fwiw.

Which gets to be very worrying when people 155 tyres on the standard (3.5" = 89mm) rims as the tyre is nearly twice the width of the rim, and although many people like that combination it is a bit of a risk.

Ah - just had a thought for iambiggles,
If you go for 165/80 tyres your rolling radius will be a bit bigger than standard!
a 165/70/14 will give the same rolling radius as the standard 145/80/14.

Post by **iambiggles** » Wed Mar 16, 2005 11:14 am

Ah - just had a thought for iambiggles,
If you go for 165/80 tyres your rolling radius will be a bit bigger than standard!
a 165/70/14 will give the same rolling radius as the standard 145/80/14.

Not an issue really as I'm replacing 175/60R13 minilites, so whatever I put on in a more traditional vein is going to be a big increase

I guess the quote on the Toyo web site for the width was for the contact width, not the tyre width..

Cheers all

Post by **Alec** » Wed Mar 16, 2005 11:20 am

Hello Ray,

"as the tyre then protects the rim flange from damage" I'm sorry but I don't follow the reasoning. Are you saying that a rubber tyre will protect a metal wheel rim?
My wife's car's tyres have a raised bead on the side wall (as I think 60's Mercedes cars used to feature) but I thought that is to protect the side wall of the tyre. Which, of course, is the more vunerable and dangerous if damaged.

Alec

Post by **rayofleamington** » Wed Mar 16, 2005 11:59 am

I'm sorry but I don't follow the reasoning.

It is fairly simple logic - when people are daydreaming and drive into a kerb at 30mph the tyre wall will squish up and take a fair bit of load over a large area (hopefully not leaving permanent damage) - if the wheel rim hits the kerb you get a point contact leading to a damaged rim and in severe cases causing a blowout.
This is why tyre places shouldn't repair punctures on the sidewall as the sidewall is a fairly saftety critical part of the tyre, and also why it is an MOT fail point to have cuts in the sidewall.

Obviously the point is that you shouldn't drive into kerbs etc at any speed.

As regards tyre width, if you don't want to believe me that is fine - feel free to check the recommendations of rim width to tyre width made by the tyre manufacturers (who would agree about the use of 165 tyres on a 5J rim).

Post by **Alec** » Wed Mar 16, 2005 12:16 pm

Hello Ray,

hmmm, I'm not really convinced. Most 'kerbing' is during low speed parking and the angle is so acute that the tyre moves and the rim scrapes the kerb. Obviously at a higher speed and with a less acute angle then the tyre will absorb a lot of the impact.
I do remember seeing tyre manufactiuurer's posters illustrating damage to tyres caused by kerbing and the internal damage was evident without very much external visible damage. Admittedly that was in the days of cross plies, so maybe radials are more tolerant.

I run 185 section tyres on 5" rims myself, but on my Triumph 2000. This was standard fitment although the standard Triumph (sorry) wheel is a 4 1\2" rim. I would have fitted 175 had I been able to get them at the time, as I am not a big believer in wide rubber. How many people actually suffer lack of adhesion on public roads?.

Alec

Post by **Cam** » Wed Mar 16, 2005 1:09 pm

WOW!! I use a 185 section tyre on a 5 1/2" rim and it looks too podgy! a 175 is a much better fit. I would not consider that on a 5" rim. I think my MGB Rostyle rims are 5" and I use 165s on there. They look very slightly podgy but I would not go wider as the sidewall 'rolling' would be too much.

Post by **rayofleamington** » Wed Mar 16, 2005 1:12 pm

Most 'kerbing' is during low speed parking and the angle is so acute that the tyre moves and the rim scrapes the kerb.

Yes - that is kerbing, but I wasn't reffering to low speed parking. If you saw how they test cars before they are released into the market it would make most people shake and need to sit in a dark room.
Some of the test tracks have a 'kerb island' which is a set of kerbs that you drive over at different angles and fairly high speed. If the standard steel rim is dented leading to a blow out I expect the car goes back to the drawing board, as that is a very dangerous thing to happen at speed. As wide alloys and low profile tyres are such a fashion accessory I guess they turn a blind eye to the ease of damage. But anyway I'm drifting into the subject of alloys vs steels and don't need to go there.

I am not a big believer in wide rubber. How many people actually suffer lack of adhesion on public roads?.

You mean all the people that say 'I need wider tyres as these things are terrible' instead of 'I'm not a very good driver' ;-)

Post by **Alec** » Wed Mar 16, 2005 4:07 pm

Hello Cam,
the tyres don't look bad at all on the rim and as I say Triumph fitted 185 section on 4 1\2" rims on the P.I. model. As an aside, it is a very good and undervalued classic with good handling, comfort and good performance especially in P.I. form (as mine is).

Alec

Post by **Cam** » Wed Mar 16, 2005 4:23 pm

Alec, I'd have to see that!

It SOUNDS like it would look like a baloon!

But if you say it's OK then it must be

Oh and I'm afraid I don't agree with you on the Triumph issue as personally I can't stand them.

The only one I would perhaps go for is a spitfire, but I was put off by the transverse rear springing arrangement. I bought an MG Midget instead

The MG vs. Triumph argument is a very old one and I think we should agree to differ, but I'm an MG man.

But a Morris man first!

Post by **rayofleamington** » Wed Mar 16, 2005 4:43 pm

WOW!! I use a 185 section tyre on a 5 1/2" rim and it looks too podgy!

So you've never seen a 185 tyre on a standard minor rim then??

My 8cwt Van had one of those

It only had 1 wide rim, and 4 others were standard rims with nasty 165's on them. I guess someone had presumed they were wide rims before fitting the wide tyres

Post by **Alec** » Wed Mar 16, 2005 5:22 pm

Hello Cam,

everyone to his own, but I suspect you have never driven one. I would not look at a Spitfire, the TR sportscars are more in my line but the saloon is, potentially, more of a performance car than all of those because of it's very strong body shell. I don't suppose you know that they won the World Cup Rally all those years ago. I know the history books will say Hannu Mikola in an Escort , but he had an illegal gearbox change which was not detected until after.

Alec

Post by **rayofleamington** » Wed Mar 16, 2005 5:54 pm

everyone to his own, but I suspect you have never driven one.

I just don't know what it is about the Triumph cars of the 70's but there's a whole load of people who really don't like them - without ever being in one or knowing much about them.
A friend has a concours Stag V8 and although it is a nice example I'm sure it would be worth many times the ££££ if it had a Jag badge, or most other badges!

Post by **bigginger** » Wed Mar 16, 2005 6:20 pm

Oh come on - you must be aware of the Stag's reputation and the reasons it got it. If it had a Jag/Rolls Royce/BMW/Morris badge it would have got the same reputation if the build quality had been as bad as it was with a Triumph badge... and yes, I have been in one and know a litttle about them.

Post by **Alec** » Wed Mar 16, 2005 6:31 pm

Hello Ray\Andrew,

the Stag's engine is basically what let it down, but compare the market values of Stags against the big saloon and that gives some indication of how undervalued the saloons are.
Don't forget also, that Jaguars have had a chequered history regarding build quality, MK 2's are still sought after but things like panel fit were terrible.

Alec

Post by **bigginger** » Wed Mar 16, 2005 7:24 pm

V. true, but a lot of the engine problems were down to build quality, most notably casting sand left in the block which didn't help a borderline cooling system! They're OK if they have money spent on them (apparently - I've read they're rather good if they're rebuilt/blueprinted). I'd still rather have one than any modern!
I've always quite fancied a Spitty too - but the Vitesses/Heralds/GT6s/2000s/TR7s leave me stone cold