Bumps from rear wheel

Thowdfella · Post by **Thowdfella** » Tue Nov 13, 2018 6:48 pm

I have a 2008 Z4 2.5 auto which isnt used very much. When I get it out of the garage and drive up the road there is a bump from - I think -
the offside read tyre. Its as if there is something on the tyre so each revolution I get this bump. I have jacked the wheel up and there is nothing there. I now find if I drive for a short while ie 2-3 minutes, the bump goes and doesnt come back until I next get it out of the garage cold. Any ideas?

buzyg · Post by **buzyg** » Tue Nov 13, 2018 8:59 pm

Rear/parking brake grabbing a little maybe. Try swapping the rears and see if it moves across.

Thowdfella · Post by **Thowdfella** » Wed Nov 14, 2018 10:04 am

2008 z4 2.5 auto. Only done 12000 miles. Recently when I get the car out there is a bump from rear offside tyre as if there is a blister or something in the tyre. Jacked it up and checked but nothing there.
Tried it again and the bump has gone away. Yesterday went shopping and when we set out for home the bump was back. Kept going and in two to three minutes bump disappeared. With the low mileage this car has spent a lot of time sitting in the garage and they are the original ride flat tyres - now 8 years old. Any ideas?

Chris_D · Post by **Chris_D** » Wed Nov 14, 2018 10:56 am

Tyres degrade. The internal laminations and cable structure will have lost significant structural integrity over that time, especially with infrequent use.
In engineering it's referred to as cyclic load fatigue.
Essentially, it's the method that big faker Uri Geller used to bend his spoons. You don't see the effect necessarily but the effects can be catastrophic. In his case, nothing left to stir his rose hip tea with!

Yorkie Z · Post by **Yorkie Z** » Wed Nov 14, 2018 11:30 am

Chris_D wrote: ↑Wed Nov 14, 2018 10:56 am Tyres degrade. The internal laminations and cable structure will have lost significant structural integrity over that time, especially with infrequent use.
In engineering it's referred to as cyclic load fatigue.
Essentially, it's the method that big faker Uri Geller used to bend his spoons. You don't see the effect necessarily but the effects can be catastrophic. In his case, nothing left to stir his rose hip tea with!

That did make me chuckle

Nictrix · Post by **Nictrix** » Wed Nov 14, 2018 12:40 pm

If your tyre has been low on pressure or flat and ran like that, even for a short distance, it can damage the side wall of the tyre which can result in the bump/blister in the tyre that you have noticed.
Your tyre is unsafe and should be replaced.

synthedup · Post by **synthedup** » Wed Nov 14, 2018 1:04 pm

Maybe a sticky caliper or hand brake?

MACK · Post by **MACK** » Wed Nov 14, 2018 1:11 pm

If the car isn't run/moved for long periods of time the tyres can flat spot where they contact the ground. When I say long periods in some cases a matter of days can cause this. The fact that it goes away after a few miles would probably indicate this is whats happening.

Failing that and particulalry if your still using run flats I would be looking for a tyre bulge. These are very common even with the best quality run flat tyres and their reverence increases with larger wheel sizes.

Thowdfella · Post by **Thowdfella** » Wed Nov 14, 2018 1:35 pm

Thanks for the replies. When I had a touring caravan I always changed the tyres after 6 years because they then started to blow - even with a full tread on. Whilst there are no bulges I think I will have to bite the bullet and replace them - but as this is the sports version I think I will go on to standard tyres rather than ride flats.

Kevoz4 · Post by **Kevoz4** » Wed Nov 14, 2018 2:16 pm

Thowdfella wrote: ↑Wed Nov 14, 2018 1:35 pm Thanks for the replies. When I had a touring caravan I always changed the tyres after 6 years because they then started to blow - even with a full tread on. Whilst there are no bulges I think I will have to bite the bullet and replace them - but as this is the sports version I think I will go on to standard tyres rather than ride flats.

Hi
I always use something similar to these https://www.leisureoutlet.com/tyre-save ... gL0R_D_BwE for my TR6, they seem to work for me.

kis · Post by **kis** » Wed Nov 14, 2018 2:37 pm

Flat spot as mentioned. Could also have been enhanced caused by low pressure? Have you checked them?

~~If you say it's been sat a long time then you probably want to replace the tyres anyway unless you've been keeping on top of pressures and rotating periodically.~~ Scratch that. They're runflats, replace ASAP! lol

Thowdfella · Post by **Thowdfella** » Fri Nov 16, 2018 12:50 pm

Just to update everyone on this. I have just had four new tyres fitted - Goodyear Eagle F1 asymmetric, non ride
flats. Noticeably more comfortable and a bit quieter and can't notice any additional roll either.
Looked for the cheapest price fitted on the web then went to my local STS Tyre Pro who matched the price.
They also gave me a print out of wheel camber and toe in which showed my rear wheels camber at-1 degree, 56 minutes and toe in 0.17 which apparently is out of alignment as it was in red figures. The front was OK.
Didn't have them corrected as quite expensive.
Incidentally, the bump was a nail in the tyre.

firebobby · Post by **firebobby** » Fri Nov 16, 2018 8:30 pm

That must have been a bloody big nail

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