Hello everyone, when I bought my car (2009 1.4 tdci) it had 175/65/15 tyres on, I popped into my local friendly tyre fitted he told me they were wrong and it should have 195/50/15's which blackcircles confirmed, I haven't needed any new tyres yet (touch wood) but with ebay having 15% off today it makes 4 toyo proxes £115 delivered and another £40 for fitting.  Would the tyres I currently have on have any negative impact on the cars handling? As the steering feels very light.

Thanks in advance!

the height of the tyre (from rim to tread surface) on 175/65 is 175mm x 65% = 113.75MM.     for 195/50 it is 97.5mm.  so it is 16mm higher.  doing a bit more maths shows that the rolling circumference of yours is about 5.6% more than the correct tyre, so your speedo will be reading about 5.6% too slow.   It won't be exactly that due the way the weight of the car squishes the tyre and it might squish it more on yours than the correct tyres.

The benefits to you might be 

higher gearing by 5% so better mpg.

less road noise as narrower tyre

more comfort as more tyre to squish out the bumps of the road

less chance of damaging rim on potholes as higher tyre offers more protection

less chance of scraping rim on kerb as higher tyre keeps rim higher up.

perhaps previous owner did it for one or more of these reasons

Disadvantage might be - will the tyre rub on something when suspension goes down over bumps or with heavy loads including steering on full lock. 

I don't know if it might affect the handling/steering, or if the tyres look a bit stretched on the rim like they are not really wide enough.

 

someone will probably tell you that your insurance company could be funny about it if you had an accident but I don't think they would succeed if you could convince them it was like that when you bought it and you  did not know. 

Thanks for the detailed reply, I went to see my local tyre fitter who said he couldn't even get the tyres himself for that price so that and the fact the eBay code was due to run out soon made me go for it, arriving Tuesday, will update once fitted to see if there's any difference.

Which Proxes?  Hopefully not T1-Rs if you ever go out in the wet...

 

one thing to bear in mind is that one of the settings in forscan gives you the ability to change tyre sizes and total circumference. if the previous owner has done this changing the tyres back may through the speedo out. I've never played around with this setting but it does show its easily possible to recalibrate the speedo for different tyre sizes.

On 8/17/2018 at 7:31 PM, TomsFocus said:

Which Proxes?  Hopefully not T1-Rs if you ever go out in the wet...

 

Surely they can't be worse than what I currently have on it lol

On 8/17/2018 at 8:01 PM, cjay1 said:

one thing to bear in mind is that one of the settings in forscan gives you the ability to change tyre sizes and total circumference. if the previous owner has done this changing the tyres back may through the speedo out. I've never played around with this setting but it does show its easily possible to recalibrate the speedo for different tyre sizes.

Is tunnel rat still the go to for modified elm327 adapters? It's about time I picked one up, I think I'll go for a usb one.

I got mine from there but it was probably between 1 & 2 years ago. it workd fine (modified USB, use with my laptop)

4 hours ago, BP2411 said:

Surely they can't be worse than what I currently have on it lol

Depends what brand and model they are...skinny Michelins are probably better than wider T1-Rs lol.  If the tyres were exactly the same model, changing to wider ones will increase the weight of the steering, increase the fuel consumption and reduce the acceleration.  You should have more grip through the corners though.  

But on the subject of T1-Rs, they were the first set of tyres I ever bought brand new (back in 2010!) on forum recommendations and was so disappointed.  Really awful in the wet.  Squealy in the dry.  Poor fuel consumption and wore out very quickly on my slow 75bhp petrol...  It's all personal preference though.  

Ahhh man you lot really know how to p*** on my chips lol, tempted to cancel them now as they haven't been dispatched yet.

Quick update, got them fitted yesterday, £40 for all 4 fitted & balanced and it feels like a totally different car, much more grounded and it feels nowhere near as light on the front end.

For anyone considering the same tyres, I drove my car in heavy rain yesterday and it felt just as good as in the dry, maybe Tom got a bad set, I got a good set or it's just a vast improvement on what was on there lol.

Or maybe you drive like less of an a**e than I do...  I'm not slowing down for a bit of rain, pfft...

But seriously, if you're happy with them then that's great, it is down to personal preference and jokes aside I do push cars hard, even in the wet as it's often wet here, so like to have confidence from tyres that I didn't get with the T1-Rs.

Of course it's possible that they've improved the compound in the last 9 years as well, you'll have to let us know how well they wear and what the wet grip is like once they've dropped a few mm.