Tyres - Newbie Help Needed Urgently!

[highlander]

Hi there,

I received my alloys with tyres today. The original eBay listing was for 4x Peugeot 307 alloys with 195/65/R15 tyres, 2 of which were illegal, the other 2 being borderline. The seller offered to replace the tyres for an extra £40.

The tyres were replaced, and the new ones are in good shape (no bulges or cracks on the sidewalls, and plenty of tread depth across all parts of each tyre) - but they are 185/65/R15, not 195/65/R15.

What does this mean to a layperson like me? Thinner tyre, meaning less grip? Or what?

If they're OK, then I'll just get them fitted as they are - if not, then I'll need to raise a query with the seller. I'd really appreciate a couple of pointers on tyre suitability.

Mine's the 406 LX 1.8i Saloon (D9), if that matters.

Kind regards,
Graeme

[DaiRees]

Have a play with this fella

You're looking at 10mm less tread width and about 2% less circumference, so in reality you probably wouldn't really notice the difference. If you are going to use them make sure you use the same size tyres on the same axel, I'd be tempted to put the 185s on the rear.

Personally I wouldn't use them though and I'd blow a fuse with the seller! I hate the thought of having different sized tyres on the car, but then again I'm known to be a bit picky when it comes to tyres

[jasper5]

The 185 is the tyre width.

The 65 is the depth of tyre on the sidewall, ie, from the rim to the edge of the tread.

R15 is the wheel diameter, ignore the R bit unless other tyres have H or V.

You must have the same size tyres on the same axle, eg, 185/65/R15 on the front with 195R15 on the back, not 185/65/R15 on the left and 195/65/R15 on the right.

I would like mine all the same size.

[highlander]

Thanks guys, I'll query it with the seller, but as long as I'm not doing anything that is gonna get me killed , I'll use them (all 4 are the same size - 185/65/R15) and just get some kind of part refund from the guy or something (I'll need to replace my spare tyre as it is 195/65/R15 (it's also a standard steel wheel)).

I guess I will also need to get the speedo recalculated as the tyres will be slightly smaller

[highlander]

Dude has given me £25 rebate (replacing the duff tyres originall on the alloys cost me £40), and has told me I don't need to worry about the speedo; he says it won't affect it.

I'm not sure I believe him, having looked at the tyre size calculator site (great link, thanks DaiRees!) it tells me that:

195/65/R15
Revs per Mile: 832.6

185/65/R15
Revs per Mile: 850.3

Does that not mean the speedo and mileage clock will be inaccurate without recalibration?

I'd love to get this straight in my head, as I'll be phoning garages tomorrow to get the new wheels fitted, and I don't want to end up paying for something I don't need.

Kind regards,
Graeme

[DaiRees]

Ah I thought you had 2X 195s and 2X 185s....

RE: the speedo, it'll read about 2% too fast, but speedos always read up to 10% too fast anyway, so that shouldn't be a problem really. Mine's about 5% over, when the gps says I'm doing 70, the speedo reads about 74. If it was the other way 'round that could get you some tickets, but this way 'round it's safe....

Incidentally I changed the tyres on my suzuki jeep from 195 80 15s to 215 80 15s, 5% bigger circumference. Result is the speedo's spot on to the GPS now