[TJBurr]

I recently bought a set of 400M wheels with tyres for £450.

They arrived today and I’ve seen both rear wheels have ContiSport Contact 5 SSR on, which after research I found retail for around £200 each. They are both worn, one to around 4 mm and the other around 5 mm. FYI they are 255/40 R18 95Y runflats.

The front wheels came with a pair of Joyroad Sport RX6 on, which after research are a budget pair of tyres around £70 each. They are worn however to around 7mm. FYI they are 225/40 R18 95W XL non runflats.

I have been quoted £100 for fitment, balancing and changing the TPMS from the old wheels to the new.

As you can see the rear tyres are runflats whilst the front non-runflats, would fitting these have any issues? Would you guys suggest getting them fitted for £100 as they have a fair bit of life still in them or splash out the cash and get 4 new normal tyres?

[njdangelo]

Definitely get 4 new tires from a decent brand. Run Flat or non flat is a personal preference but you always want to make sure your tires match.

[Desertnate]

Agree, use this as an opportunity to get good tires on all four corners.

I don't know what the ride or handling might be like with a tire type mismatch (run flat vs non), but there could be some real grip issues with a mismatched tire set, especially some budget brand. Are they even the same speed and load rating?

[TJBurr]

Originally Posted by Desertnate

Agree, use this as an opportunity to get good tires on all four corners.

I don't know what the ride or handling might be like with a tire type mismatch (run flat vs non), but there could be some real grip issues with a mismatched tire set, especially some budget brand. Are they even the same speed and load rating?

I didn’t think front and rear tyres had to have the same load and speed rating, as long as they are above the threshold of the weight of the car+speed intended on travelling at?

[cfm56d7b]

Originally Posted by TJBurr

I didn’t think front and rear tyres had to have the same load and speed rating, as long as they are above the threshold of the weight of the car+speed intended on travelling at?

There are so many variables in the picture when the vehicle has both run flat and go flat tires: compound differences, wet / dry handling differences, sidewall stiffness, tread wear.

In short - not recommended by a wide margin.

This is a very good opportunity to get new tires, whether run flat or go flat.

[njdangelo]

Originally Posted by TJBurr

I didn’t think front and rear tyres had to have the same load and speed rating, as long as they are above the threshold of the weight of the car+speed intended on travelling at?

Disagree with this whole heartedly. Different speed rating tires have different weights, different compound, different longevity, etc.

[therealm3]

Agree with what others have stated. Don't mix and match brands of tires. You are setting yourself up for weird driving characteristics. With that said, you "can" do it and the car will still drive ok, but why bother? If a couple hundred is that hard to come by for arguably the most import item on a car as it's literally the only part touching the ground, maybe you are driving the wrong car? If we are talking temporary hardship and you just need to get by for a bit, yeah, you'll be fine. Just take it easy on the car and match them up as soon as you can.

[Sigtran]

Mixing, as you suggested, technically, for short period of time and slower and careful driving might work as a temporary workaround, but really not recommended since big difference in tyre characteristics would negatively impact handling, so safety first!

And even a 320D ED is a performance handling car thus recommendation is buying a full set of decent tyres (RFT or non-RFT choice it is up to you) so you could safely and with a piece of mind enjoy driving it every day.

[BWbimmer]

7mm is as good as new. So if you don't mind a budget tire you could get yourself the same for the rear?
Mixing dffrent types and brands is a nogo. You would not enjoy the ride.
But since you got the wheels for a fair price I would invest in a good set of new tires

[Desertnate]

Originally Posted by njdangelo

Disagree with this whole heartedly. Different speed rating tires have different weights, different compound, different longevity, etc.

Yes! The different speed ratings and rubber compounds will lead to very different levels of grip which will effect the handling and the behavior of the car while in motion. Add temperatures or even wet roads where the tires will evacuate water differently and you could have a wild ride. Different load ratings, even if they meet/exceed the vehicle requirements will behave differently as well under load while driving.

I actually experienced a situation like this first-hand. Last year I ran into issues while swapping out my summer/winter tires (long story). This lead me to drive my car about 3.5 miles to my local mechanic with my winter set on the front and the summer set on the rear. It was NOT a fun experience. Even though all four corners met BMW's specs the car's handling even in gentle urban driving was really unsettling. Granted, my example is a bit extreme, it still shows that simply meeting specs isn't everything.

[paulymu]

I agree with the others. Get a new set and save yourself the headache. Run flat or not is up to you. Run flats tend to be a bit more pricey but idk where you're located so it may be different.

[MmmmmM2]

I switched out my RFT Potenza's for some Pilot Sport 4S and have never regretted it.

[cfm56d7b]

Originally Posted by Desertnate

Yes! The different speed ratings and rubber compounds will lead to very different levels of grip which will effect the handling and the behavior of the car while in motion. Add temperatures or even wet roads where the tires will evacuate water differently and you could have a wild ride. Different load ratings, even if they meet/exceed the vehicle requirements will behave differently as well under load while driving.

I actually experienced a situation like this first-hand. Least year I ran into issues while swapping out my summer/winter tires (long story). This lead me to drive my car about 3.5 miles to my local mechanic with my winter set on the front and the summer set on the rear. It was NOT a fun experience. Even though all four corners met BMW's specs the car's handling even in gentle urban driving was really unsettling. Granted, my example is a bit extreme, it still shows that simply meeting specs isn't everything.

Adding only one more comment to what Desertnate has summarized so well. Life is not a dress rehearsal. Please get 4 new tires and enjoy the vehicle.

[Wires]

Originally Posted by therealm3

Agree with what others have stated. Don't mix and match brands of tires. You are setting yourself up for weird driving characteristics. With that said, you "can" do it and the car will still drive ok, but why bother? If a couple hundred is that hard to come by for arguably the most import item on a car as it's literally the only part touching the ground, maybe you are driving the wrong car? If we are talking temporary hardship and you just need to get by for a bit, yeah, you'll be fine. Just take it easy on the car and match them up as soon as you can.

Exactly want he said. You are just looking for a situation that's going to end in a bad result.

Pick the same brand of tires for all 4 corners. Even if they are junk, just make sure they match.