[sreerama]

Recently replaced the tires of Stock Celerio Diesel (2016 Nov Manufactured the last batch) with Continental CC6 aiming to get a better comfort drive back in Dec 2024.

The stock tires were Mrf zvtv 165/70-R14. The tires started cracking externally as I did not use much post Covid and also due to the age. It had served 60k kms but still had tire wear indicator left & could serve maybe for another 10-15k. The recommended tire pressure is 36F/34R & I maintained 35F/33R.

Post replacement felt softer with good roads with increased stability & confidence to drive in high speed but once I switched to broken patches got more road imperfections transferred inside the cabin which was minimal with Mrf.

When I used the same air pressure of 35F/33R, the ride quality was harsh in broken Bangalore roads. As suggested by Maruti service & Fng, reduced the air pressure to 33F/31R when did reduce the feel of potential holes but still transferred a lot into the cabin. Maruti service advisor suggested sturts replacement as it could have become weak but no oil leaks noticed. I did replace the Sturts and link rods, bushes etc which did not resolve the original issue and it did create more noise in full turns at an angle which I am yet to resolve as I am not satisfied with the replacement work. Actually it made the driving little more harder due to new Struts. The technician who worked on my vehicle clearly said it's the tire which is causing this issue and the suspension is not able to handle. Asked me to switch to the OEM recommended ones if the issue doesn't get resolved.

I drove for 3800 kms till now to see if this issue settles settles with tires and struts but it has not. I have started to check on the tires and unsprung weight now which started this issue.

[sreerama]

I still had my old Mrf rubber lying around and measured it's weight with body measurement Mi weighing scale, it was between 6.1-6.3 kgs.

All the tire shops I had enquired here in Bangalore suggested me to stay away from Mrf as it's a hard compound and suggested Yokohama or Continental especially if my focus was comfortable drive. Maybe they are partially right but I am sure now it's not built for light weight cars like Celerio which weights 880-900 kgs for the Diesel(little more than the petrol). Coming back to the topic of unsprung weight and wrist press on the tread to check the flex, here are the results.

Continental CC6 - 7.5 Kgs, wrist press flex starting (crown area or contact patch) weight measured 22.6 ~ kgs approximately but doesn't flex like Yokohama or Mrf for sure.

Yokohama Earth 1 - 7.8-7.9 Kgs, wrist press flex starting (crown area or contact patch) weight measured 19+ ~ kgs approximately

Mrf Zvtv new - 6.3-6.5 Kgs, wrist press flex starting (crown area or contact patch ) weight measured 18 ~ kgs approximately

Mrf Zlx - 6.9-7.1 Kgs, wrist press flex starting (crown area or contact patch) weight measured 18.5+ ~ kgs approximately

Mrf zvtv(not sure) 155/80-13 - 6-5 Kgs, wrist press flex starting (crown area or contact patch) weight measured 20+ ~ kgs approximately. Did not check much but tried this as this was the stock size in base variant and wanted to check what weight the suspension might have been turned for..

Here it looks like Mrf zvtv 165/70-14 is manufactured Close to the 155/80-13 inches tire weight to balance out the unsprung weight and also to provide better flex to compensate the reduced sidewall thickness.

I had driven a Celerio (petrol) which was replaced with Apollo 4G and the drive was quite absorbent. I will have to check the Apollo tire similarly to make a comparison which might not cover everything but atleast the basics I what I am hoping for.

For reference Celerio Diesels suspension is stiffened by default to handle the additional weight and the steering is not light either which does improve highway driving stability.

1. The question here is why people usually term continental CC6 or in general Continental as a better tire for bad roads to absorb bumps/potholes or the first thing tire shops suggest when Mrf has a better flex to handle road undiluations?

2. Does this unsprung weight impact driving experience over broken road patches? Chat gpt says it does impact suspensions ability to handle and react efficiently or as designed. I have upsized scooters tire from 90/100-10 to 110/90-10 and it does take a hit on bad roads but offers better grip at straight line as well as corners. But here for the car, I have not performed any upsizing.

3. How does this wrist flex test say about the contact patches absorption abilities? I know this is not doyin an inflated tire but I guess these are the ones I could try as I don't want to go with Tire shops as usual they are very confident about the brand or tire as a who package rather than considering my use case scenario.

I will try to swap conti to my old mrf tires to check how much difference it could make in the front end. Not sure how many takers will be there for just 3.5k run continental tires, already nearby Mrf, Bridgestone tire shops are not interested in taking exchange for these tires as they usually take only scrap value even though it's almost new.

[sreerama]

Pictures for reference for 165/70-14 inches size.

Conti CC6, please excuse as it's not clear with the readings.


Wrist flex weight for CC6


Earth 1 E400 tire weight


Wrist flex weight for Yokohama Earth 1


Mrf Zvtv


Wrist flex weight for zvtv tire


Mrf zlx tire weight


Wrist flex weight for zlx


I am not sure how many people will be interested in to these details but thought of posting as it could turn out to be useful for someone someday.

[mohan41]

Originally Posted by sreerama

...I had driven a Celerio (petrol) which was replaced with Apollo 4G and the drive was quite absorbent. I will have to check the Apollo tire similarly to make a comparison which might not cover everything but atleast the basics I what I am hoping for.

If you search the S-presso official review thread, our member Dr. Abhi has mentioned his nice experience with Apollo Amazer 4G which were changed after running on Stock MRF tyres for 22K km.

https://www.team-bhp.com/forum/offic...ml#post5926474 (Maruti S-Presso : Official Review)

[Transmission]

I dont have much to add to this thread, but I wanted to appreciate how you have diligently measured parameters instead of blindly putting out opinions that are not easy to judge.

One factor that can affect comfort but might not have made itself obvious in your measurements is the rate of rebound of the tyre wall. Good suspension is a fine balance between being compressible as well as the rate and duration of rebound.

[bikertillidie]

1 kg (appx) difference in tyre mass should not make such a huge difference in suspension feel.

Apart from replacing the dampers and adjusting tyre pressures which you have already done, could you possibly get the suspension bushes and strut mounts checked. They tend to stiffen over time.... New bushes with appropriate lubrication may help.

[sreerama]

Originally Posted by bikertillidie

1 kg (appx) difference in tyre mass should not make such a huge difference in suspension feel.

Apart from replacing the dampers and adjusting tyre pressures which you have already done, could you possibly get the suspension bushes and strut mounts checked. They tend to stiffen over time.... New bushes with appropriate lubrication may help.

I think these were all checked and replaced/lubed.



Here is the list of components changed, the RH strut was purchased from nearby Genuine Suzuki spares as the order received item from the service centre side had same LH side instead of RH. I do get additional noise from the top side of front suspension when the vehicle is turned at an higher/lower angle for eg with left on top/ right below or vice versa after the parts replacement.
Service centre people told me the bushes were replaced even though it looks good as it's an one time activity.

The lower arms were not replaced as they mentioned it's looking good.

I had swapped the front 2 tires with 8+ year old mrf zvtv tires which I had retained. Air pressure filled was 34F/31R.
Able to have a much better ride over pot holes/ speed breakers absorption(without transferring it hardly inside the cabin/seats) with a lighter steering. I stay near Garden city University where the roads are bad / non existing or completely broken with lots of speed breakers which are not smooth or built with better approach angle.

[self_driven]

Originally Posted by sreerama

For reference Celerio Diesels suspension is stiffened by default to handle the additional weight and the steering is not light either which does improve highway driving stability.

Increase in unsprung mass has a negative effect on vehicle dynamics due to rolling momentum. In layman terms, the car will see a 4 kg increase (1 kg per tyre) as 8 kg of additional weight to carry. This only results in slower acceleration, poor braking and harder steering feel, so either there has to be a substantial increase in weight (20-25 kg unsprung) or something wrong with the suspension/tyres to result in a noticeably worse ride quality.

I'm pretty sure the CC6 you've got are defective. Otherwise, how can one explain 8 year old MRFs tackling bad roads better than new Continentals?

First and foremost, you should check the manufacturing date on all tyres to make sure they are not too old. Next, swap the front and rear tyres once to see if the problem is limited to a particular tyre or not.

From your last post, I could infer that you already have the front CC6 off the rims, visit a tyre shop and compare the tyres you have with other CC6s' in that store. The weighing scale will come in handy here.

If there are no unusual findings, as a last resort, raise a warranty request with Continental and let their engineers inspect the tyres and give a verdict.

[bikertillidie]

Originally Posted by sreerama

I do get additional noise from the top side of front suspension when the vehicle is turned at an higher/lower angle for eg with left on top/ right below or vice versa after the parts replacement.
Service centre people told me the bushes were replaced even though it looks good as it's an one time activity.

The lower arms were not replaced as they mentioned it's looking good.

I had swapped the front 2 tires with 8+ year old mrf zvtv tires which I had retained. Air pressure filled was 34F/31R.
Able to have a much better ride over pot holes/ speed breakers absorption(without transferring it hardly inside the cabin/seats) with a lighter steering..

Any noise while negotiating turns indicate

(a) issue with strut bearings and / or
(b) steering rack issues and / or
(c) drive shaft CV joint issues

How can 8 year old tyres perform better than new ones? This is very odd indeed.

Please get the wheel alignment checked at a specialist store. Hope the tyre dimensions match and steering geometry hasn't been negatively impacted by the tyre swap.

[sreerama]

Old MRF rubber is indeed very hard compared with CC6. The steering offset has also changed a bit due to the swap. I don't drive much as I wfh and just use it at a 5 km radius. I can feel and hear the tire noise due to the hard rubber.
The CC6 tires actually provide better confidence, great highway stability and almost nil road noise over 85-120 kms. I have never been so confident even when the car was new with zvtv, I never do above 95. In a 8 or 6 lane sections, I have done 110-120 with confidence with CC6 as it gives a surefoot feel compared to basic MRF zvtv tires. Continental CC6 is great for spirited driving there is no doubt.
I noticed that the same car can be driven faster with CC6. I use a CBR250 abs with Michelin pilot sports tires for reference. I like to feel the road to drive surefooted but not like how it feels with CC6 on broken roads now.

The above being said and with old rubber traits, the swap was done to analyse the suspension's ability to handle pot holes, road undiluations etc as these were better earlier.
As a result even though the new rubber is soft, it does transfer the impacts more inside the cabin making the drive over pot holes / road undiluations jarring especially on the cuts (similar to expansion joints on the flyover but little more bigger than that) jarring like the suspension is not able to handle or slow to react.

There could be various reasons for the amplified effect. Basically Petrol celerio weighs 810-825 kgs whereas diesel weighs 880-900. Due to the increased engine weight, springs and struts has been hardened to take the additional engine load, you can take a look at the parts list of the suspension.

This makes the steering a little bit more tighter than the petrol engine along with harder suspension. When we now use a harder construction tire to this suspension combo it makes the ride quality worse with pot holes /speed breaker filled Bangalore roads. For each 40kmph, there are speed breakers. Even the NH has so many of them, this makes the traffic worse throughout the city. I understand these are there for safety but I feel it's too much. My driving is mostly in 1st & 2nd only and max 3rd as I drive only a max of 3-4 km radius.
So the issue is not limited to these local roads, I have never felt this much tired with 350 km highways driving (Blr to Chennai/ Pondy), so these CC6 are not good for my ride if there are road undiluations.

[sreerama]

Originally Posted by self_driven

Increase in unsprung mass has a negative effect on vehicle dynamics due to rolling momentum. In layman terms, the car will see a 4 kg increase (1 kg per tyre) as 8 kg of additional weight to carry. This only results in slower acceleration, poor braking and harder steering feel, so either there has to be a substantial increase in weight (20-25 kg unsprung) or something wrong with the suspension/tyres to result in a noticeably worse ride quality.

I'm pretty sure the CC6 you've got are defective. Otherwise, how can one explain 8 year old MRFs tackling bad roads better than new Continentals?

First and foremost, you should check the manufacturing date on all tyres to make sure they are not too old. Next, swap the front and rear tyres once to see if the problem is limited to a particular tyre or not.

From your last post, I could infer that you already have the front CC6 off the rims, visit a tyre shop and compare the tyres you have with other CC6s' in that store. The weighing scale will come in handy here.

If there are no unusual findings, as a last resort, raise a warranty request with Continental and let their engineers inspect the tyres and give a verdict.

I have raised a query with continental yesterday. The manufacturing was in 4124.



I did notice some additional layer of rubber bump inside the tire which was not present in the MRF. Let me post some pics for reference.

[sreerama]

Originally Posted by mohan41

If you search the S-presso official review thread, our member Dr. Abhi has mentioned his nice experience with Apollo Amazer 4G which were changed after running on Stock MRF tyres for 22K km.

https://www.team-bhp.com/forum/offic...ml#post5926474 (Maruti S-Presso : Official Review)

I did visit Apollo tires and checked the Amazer 4G. They are heavier than MRF and little hard to flex. I have driven a celerio petrol with these and it was comfortable.

All 165/70-14
Amazer 4G weighs 7.2 Kgs


Flexing starts at 23 kgs similar to CC6


Vredestein tires were very soft. It weighs only 6.4 kgs similar to zvtv.


The flexing seems to be similar to Mrf zlx but with a lower weight and feels like a softer sidewall.


I also checked 175/65-14 which is the next upsize and surprisingly it was also weighing less with 6.7 kg.


The sidewall flex started at 19kgs and contact patch flexed later.


T-Trac 2 is not listed in their Indian website, thinking of considering these as they are weighing and flexing close to the zvtv tires. Was quoted 4100 per tire similarly priced with Continental and Yokohama. Apollo was 3800.

Not sure if I can post external link - https://www.tyrereviews.com/Tyre/Vre...n/T-Trac-2.htm
https://www.vredestein.co.uk/car-suv.../896-T-TRAC-2/