Puncture?

T

The Moo

Senior member
 Warwickshire
I am currently running Falkens on the front and Bridgestone runflats on the back until the latter wear out. When I started my car up this evening for the trip home from work the red runflat light came on. I drove home carefully and checked all of the tyres. No obvious visual signs of a puncture on the rear. I checked the pressures with a digital gauge and they were all within 5psi of each other. (between 30 and 35) I equalised the pressures using the analogue gauge on foot pump. I then did the initialization, the red light went yellow, but before I got off the drive it had gone red again and stayed red. Went for a drive (about a mile) checked the pressures and on the digital readout they were within 0.5 psi of each other. Checked the rear tyres two hours later (and they were much cooler) and on the digital pressure guage both a bit lower but still within 0.5 psi of each other.

I will check pressures again in the morning, but have I got a puncture in the runflats and if so what are the signs as the sidewalls and tread seemed rock hard? If I haven't got a puncture is it a relatively simple electrical gremlin to resolve?
 
Hi The Moo,

Sorry i don't know the solution to your problem, but i was wondering how you found the mix of falkens on the front and BS run flats on the back?

i'm planning on doing the same, as my fronts are worn and rears not. and wondered whether you have had any handling/balance issues.

i've had some people saying it's a bad idea, and others saying it makes no difference.

what's your opinion, as someone who's driven on that setup?

thanks
 
The TPS system works on wheel rotation, if pressures are correct and you havent just changed the front to non RFT's I would say there is a fault with the system.

I would think most if not all insurance companie would frown on the mixing of normal and RFT tyres though.

I always found rear grip lacking with the RTS's so adding more grip to the front cant be good.

The cost of 4 Falkens = 2 Bridgestone RFT's so just get all 4 done and benefit from the all round improvement and sote the RFT's for when you come to sell.
 
The sidewalls would feel rock hard on a RFT with a puncture, they have to support the weight of the car afterall.

As said, you shouldn't really mix RFTs and nonRFTs, you need all of the same.

I'm not 100% happy with my TPS, i got through to the canvas on one of my RFTs (I was getting rid of the full set to replace with Falkens so had a little too much fun outside. I let some air out before driving the mile to the fitters as I was worried they might pop. and the TPS didn't say anything, I then let them down fully, still nothing, I have now replaced the full set with the Falkens and still haven't heard any complaint from the TPS :?
 
TH3R4POR said:
The sidewalls would feel rock hard on a RFT with a puncture, they have to support the weight of the car afterall.

As said, you shouldn't really mix RFTs and nonRFTs, you need all of the same.

I'm not 100% happy with my TPS, i got through to the canvas on one of my RFTs (I was getting rid of the full set to replace with Falkens so had a little too much fun outside. I let some air out before driving the mile to the fitters as I was worried they might pop. and the TPS didn't say anything, I then let them down fully, still nothing, I have now replaced the full set with the Falkens and still haven't heard any complaint from the TPS :?
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The TPS measures the relative difference in rotation of tyres on the same axle. The idea being if one loses pressure it's rolling radius will decrease and thus speed of rotation. If you let noth down they will rotate the same and so no warning. Shoudl be perfect unless in you happen to go over 2 nails that let both tyres down at the same rate :)

It's also not a tread gauge so you could go right to canvas and of course no warning. Stick a brand new tyre on one side, bald ont he other and you'd get a warning.
 
The sidewalls have always felt rock hard and the car doesn't feel any diferent to how it did before the red light came on. How sensitive is the indicator? Does 1 or 2 PSI difference make it register? When I equalized the pressures (by adding air) the light still didn't go out.

I have just checked the pressures on the back again and the nearside rear is now about 1.5psi less than the offside. (Not sure about the accuracy/sensitivity of these car accessory shop digital gauges though) If there are no other obvious ways of checking then I will monitor it during the day and if it continues to go down take it to the tyre depot and get it checked out. (Might be a valve I suppose) If it is a puncture then the Falkens will be going on the back sooner than expected!

I would be royally peed off though if I changed the tyres and the light stayed on. Life seem so much simpler with normal tyres. You get a puncture you know where you stand. Now I need to first establish if I really do have a puncture.

For all those who asked I have not experienced any handling issues in the dry or wet mixing runflats and non runflats. The car is driven at motorway speeds and has behaved just fine and it handles well on the twisty stuff and stops OK. I don't treat every drive on the road like a track day experience but I enjoy driving it briskly when it is safe to do so.............but not anymore until this tyre issue is resolved.
 
cj10jeeper said:
The TPS measures the relative difference in rotation of tyres on the same axle. The idea being if one loses pressure it's rolling radius will decrease and thus speed of rotation. If you let noth down they will rotate the same and so no warning. Shoudl be perfect unless in you happen to go over 2 nails that let both tyres down at the same rate :)
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I let one down and had no alarm and I let it down because I got to the canvas. I should have had an alarm.
 
The Moo said:
The sidewalls have always felt rock hard and the car doesn't feel any diferent to how it did before the red light came on. How sensitive is the indicator? Does 1 or 2 PSI difference make it register? When I equalized the pressures (by adding air) the light still didn't go out.

I have just checked the pressures on the back again and the nearside rear is now about 1.5psi less than the offside. (Not sure about the accuracy/sensitivity of these car accessory shop digital gauges though) If there are no other obvious ways of checking then I will monitor it during the day and if it continues to go down take it to the tyre depot and get it checked out. (Might be a valve I suppose) If it is a puncture then the Falkens will be going on the back sooner than expected!

I would be royally peed off though if I changed the tyres and the light stayed on. Life seem so much simpler with normal tyres. You get a puncture you know where you stand. Now I need to first establish if I really do have a puncture.

For all those who asked I have not experienced any handling issues in the dry or wet mixing runflats and non runflats. The car is driven at motorway speeds and has behaved just fine and it handles well on the twisty stuff and stops OK. I don't treat every drive on the road like a track day experience but I enjoy driving it briskly when it is safe to do so.............but not anymore until this tyre issue is resolved.
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Did you correctly reset the light by pressing and holding the button down? It will turn the warning light amber then reset itself.

Dave - did you drive for a distance on the now deflated tyre to allow the ABS to average out left and right turns and calculate that there was a genuine difference in rotation?
 
I have tried the reset button numerous times as per the handbook. the red warning light goes to amber and then back to red.
 
Now Sorted!!!

Checked the tyres again at lunchtime. Across the axles there was about 1psi difference on both front and rear. Probably put that down to Sun beating down strongly on nearside and a work mate's Jag saloon shading the offside!

Closer inspection of rear (runflat) tyres showed that tread was down to wear bars. So after work went round to Southam Tyres and got a pair of Falkens 452s fitted. (Asking £200 but got them down to just below Black Circle quote so paid £183.00 fitted)

Red light was still on so tried to reinitialise at tyre depot to no avail and drove home thinking must be an electrical issue.

Got onto drive and had a couple more attempts and it eventually cleared. Went for a spin round the block and it stayed off and everything seemed OK. Now just looking forward to the tyres bedding in and having a decent drive, but initial thoughts are that the ride is less harsh at the back.

There appeared to be no evidence of a puncture but if the tread gets to or below wear bar could that set the sensor off or perhaps it is just an intermittent elctrical niggle?

Happy Teddy now :)
 
I think a significant difference in wear of a tyre on one side to the other would trigger it. I've managed to set mine off messing inthe snow spinning wheels.

Not convinced on the electrical fault as an issue as the sensor is the ABS sensor, so if that were not working it would throw an ABS light. Guess whichever module controls it cuold be faulty

See how you get on now with new tyres and a reset.
 
cj10jeeper said:
Dave - did you drive for a distance on the now deflated tyre to allow the ABS to average out left and right turns and calculate that there was a genuine difference in rotation?
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The tyre fitters is probably just over a mile away. I thought the TPS set an alarm within a few feet?
 
I think it depends on the amount of deflation. I did have a total flat at it did sense that in a hundred metres or so
 
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