Question about tyre-to-spring-cup clearance

[djoptix]

I didn't consider it shite enough for this forum, but last week I picked up Bertie the Berlingo, Mrs Optix's new ride. It needs two rear tyres, and I have a set of wheels from my last C5 that I was hoping to use.

 

The tyres on it are 195/65/15. The tyres on the new wheels are 205/65/15 - close but 6.35mm bigger radius. Annoyingly, the wheels on it now are already slightly bigger than standard. tl;dr the new tyres are only 2-3mm off the bottom spring cup at the front.

 

Is this too close? I think probably yes... allowing for a bit of flex under cornering, tyres expanding ever so slightly at speed/when hot...

[DodgeRover]

Try it and see if you get any marks under cornering.

[hairymel]

^this

[cobblers]

I've run loads of stuff as close as that, it should be fine

[Bucketeer]

There's a thread for questions - http://autoshite.com/topic/26894-stupid-question-amnesty/page-510

[Pillock]

I always thought the SQA thread was for ponderings and musings (like, "what was the last car to have a brown wire connecting the speedometer light to the fuse box") and we were OK to have a separate thread along the lines of "This has happened and I need someone to tell me whether kittens are going to die". Makes stuff easier to find too. Just my tuppence.

 

Anyway, I too have run stuff that close without issue. Sidewall flex tends to be at the bottom and you'll not get much lateral movement at the top.

[overrun]

I didn't consider it shite enough for this forum, but last week I picked up Bertie the Berlingo, Mrs Optix's new ride. It needs two rear tyres, and I have a set of wheels from my last C5 that I was hoping to use.

 

The tyres on it are 195/65/15. The tyres on the new wheels are 205/65/15 - close but 6.35mm bigger radius. Annoyingly, the wheels on it now are already slightly bigger than standard. tl;dr the new tyres are only 2-3mm off the bottom spring cup at the front.

 

Is this too close? I think probably yes... allowing for a bit of flex under cornering, tyres expanding ever so slightly at speed/when hot...

 

My MR2 runs fag paper close, and there are zero rubbing issues.

[djoptix]

Thanks all, and I am happy to have this deleted/moved to SQA if appropriate. BUT

 

I should have clarified I'm not talking about lateral clearance where sidewall flex would be the issue, but clearance over the tread of the tyre itself - the spring cup overhangs the tread. Does that change anyone's view on the matter?

 

Sorry, I can see how this was confusing because I'm clearly talking about tyres that are wider, but because tyre size calculations are from the devil, this means the tyre is very slightly bigger in diameter, as well as obviously being 10mm wider overall.

 

I'm aware I could put tyres on it and go and hammer it round some corners, but it isn't insured or taxed at the moment and I have no wish to put any money in the pockets of the insurance industry/the Dervla until necessary.

[DodgeRover]

I would think if you are running the correct pressures it wouldn't be an issue

[New POD]

And provided there's no free play in the bearings

[Mr_Bo11ox]

If you think the risk is on the diameter of the tyre, driving it hard round corners isn't gonna prove owt. Just drive it as fast as you dare to check for centrifugal growth and listen for funny noises/check the tyres for grooves after! If you get a whirr at 84mph you know you're limited to 83 till you've worn some tread off! Lovely!

[lisbon_road]

OK not really answering the question.  I have found before that a car fitted with the wrong size tyres just looks wrong at a glance.  I'd trade 'em at a co-operative secondhand tyre dealer for the right size, sleep well and know it looks ok.

 

Just my opinion.

[DodgeRover]

Are you sure what's on were the right size to begin with ?

[djoptix]

And provided there's no free play in the bearings

 

At least that's one thing I can be sure of, both of the bearings are brand new at vast expense.

 

 

Are you sure what's on were the right size to begin with ?

 

Excellent question sir. No, they aren't, they're slightly bigger than standard themselves.

 

 

OK not really answering the question.  I have found before that a car fitted with the wrong size tyres just looks wrong at a glance.  I'd trade 'em at a co-operative secondhand tyre dealer for the right size, sleep well and know it looks ok.

 

Just my opinion.

 

Fair point. Hmm....