Tyre Sizing Confusion

[fanx_ta_ra]

Hi All,

Need to get four new tyres and am slightly confused about sizing. I have 17" alloys and at present they are fitted with 225/55/17's but when I was getting a quote today was told that the correct size should be 225/50/17 . Have searched the archives on here and it seems that both sizes are used but surely one must be a closer match to the original 215/65/15 with regards to the speedo reading / rolling circumference. Well thats it really and just gotta say while I'm on here that the knowledge and input on here from lots of you lads and lasses makes owning a Bongo so much easier and enjoyable so well done all of you .

Cheers, Andy

[madmile]

I am pretty sure mazda never had 17" option, so if you get near enough then I am sure you will be fine. I run on 215/55/17's and have never had a problem. I also use 245/24/18 on another bongo and these are definitely bigger than standard.
As long as your load rating is correct and you dont have different sizes on the 4wd (except for mazdas accepted combination) then you should be OK.

[westonwarrior]

there is a converter in the link below put in your origonal size 195/70/15 and the new size and it compares rolling diameter etc


http://www.tyresave.co.uk/tyresize.html

225/50/17 are closer to the origonal spec than 55

[maxheadroom]

try this link it should help.....

http://www.kouki.co.uk/utilities/visual ... calculator

[missfixit70]

The 55 profile should be a slightly more comfortable ride, main thing as Madmile said is to makes sure Load & Speed Rating are a minimum of 96S. The speedo is usually fairly inaccurate anyway.

[francophile1947]

I've used 225/55x17 tyres and am currently using 225/50x17. Per the satnav, the speedo very slightly under reads with the 55 profile and slightly over with the 50 profile. Therefore, technically, the 55s are illegal as your speedo should never read slower than you are actually going. However, I don't think 1mph at 70mph is too crucial Can't say I've noticed much difference in the ride quality, but my van is hardly fitted with the standard suspension

[Scott]

I was playing around with a tyre converter and it spilled this out, all of these tyres sizes are compatible

Code: Select all

Tyre	     Wheels	    Width	         Height	    Height Difference
165/85 R 15	15"	6.50" (165mm)	26.04" (661.50mm)	+0.04" (+1.00mm)
175/80 R 15	15"	6.89" (175mm)	26.02" (661.00mm)	+0.02" (+0.50mm)
185/75 R 15	15"	7.28" (185mm)	25.93" (658.50mm)	-0.08" (-2.00mm)
200/70 R 15	15"	7.87" (200mm)	26.02" (661.00mm)	+0.02" (+0.50mm)
215/65 R 15	15"	8.46" (215mm)	26.00" (660.50mm)	+0.00" (+0.00mm)
230/60 R 15	15"	9.06" (230mm)	25.87" (657.00mm)	-0.14" (-3.50mm)
235/60 R 15	15"	9.25" (235mm)	26.10" (663.00mm)	+0.10" (+2.50mm)
255/55 R 15	15"	10.04" (255mm)	26.04" (661.50mm)	+0.04" (+1.00mm)
280/50 R 15	15"	11.02" (280mm)	26.02" (661.00mm)	+0.02" (+0.50mm)
310/45 R 15	15"	12.20" (310mm)	25.98" (660.00mm)	-0.02" (-0.50mm)
160/80 R 16	16"	6.30" (160mm)	26.08" (662.40mm)	+0.07" (+1.90mm)
170/75 R 16	16"	6.69" (170mm)	26.04" (661.40mm)	+0.04" (+0.90mm)
180/70 R 16	16"	7.09" (180mm)	25.92" (658.40mm)	-0.08" (-2.10mm)
195/65 R 16	16"	7.68" (195mm)	25.98" (659.90mm)	-0.02" (-0.60mm)
210/60 R 16	16"	8.27" (210mm)	25.92" (658.40mm)	-0.08" (-2.10mm)
230/55 R 16	16"	9.06" (230mm)	25.96" (659.40mm)	-0.04" (-1.10mm)
255/50 R 16	16"	10.04" (255mm)	26.04" (661.40mm)	+0.04" (+0.90mm)
280/45 R 16	16"	11.02" (280mm)	25.92" (658.40mm)	-0.08" (-2.10mm)
285/45 R 16	16"	11.22" (285mm)	26.10" (662.90mm)	+0.09" (+2.40mm)
315/40 R 16	16"	12.40" (315mm)	25.92" (658.40mm)	-0.08" (-2.10mm)
320/40 R 16	16"	12.60" (320mm)	26.08" (662.40mm)	+0.07" (+1.90mm)
165/70 R 17	17"	6.50" (165mm)	26.09" (662.80mm)	+0.09" (+2.30mm)
175/65 R 17	17"	6.89" (175mm)	25.96" (659.30mm)	-0.05" (-1.20mm)
190/60 R 17	17"	7.48" (190mm)	25.98" (659.80mm)	-0.03" (-0.70mm)
205/55 R 17	17"	8.07" (205mm)	25.88" (657.30mm)	-0.13" (-3.20mm)
210/55 R 17	17"	8.27" (210mm)	26.09" (662.80mm)	+0.09" (+2.30mm)
225/50 R 17	17"	8.86" (225mm)	25.86" (656.80mm)	-0.15" (-3.70mm)
230/50 R 17	17"	9.06" (230mm)	26.06" (661.80mm)	+0.05" (+1.30mm)
250/45 R 17	17"	9.84" (250mm)	25.86" (656.80mm)	-0.15" (-3.70mm)
255/45 R 17	17"	10.04" (255mm)	26.04" (661.30mm)	+0.03" (+0.80mm)
285/40 R 17	17"	11.22" (285mm)	25.98" (659.80mm)	-0.03" (-0.70mm)
290/40 R 17	17"	11.42" (290mm)	26.13" (663.80mm)	+0.13" (+3.30mm)
325/35 R 17	17"	12.80" (325mm)	25.96" (659.30mm)	-0.05" (-1.20mm)
170/60 R 18	18"	6.69" (170mm)	26.03" (661.20mm)	+0.03" (+0.70mm)
185/55 R 18	18"	7.28" (185mm)	26.01" (660.70mm)	+0.01" (+0.20mm)
200/50 R 18	18"	7.87" (200mm)	25.87" (657.20mm)	-0.13" (-3.30mm)
205/50 R 18	18"	8.07" (205mm)	26.07" (662.20mm)	+0.07" (+1.70mm)
225/45 R 18	18"	8.86" (225mm)	25.97" (659.70mm)	-0.03" (-0.80mm)
230/45 R 18	18"	9.06" (230mm)	26.15" (664.20mm)	+0.15" (+3.70mm)
250/40 R 18	18"	9.84" (250mm)	25.87" (657.20mm)	-0.13" (-3.30mm)
255/40 R 18	18"	10.04" (255mm)	26.03" (661.20mm)	+0.03" (+0.70mm)
285/35 R 18	18"	11.22" (285mm)	25.85" (656.70mm)	-0.15" (-3.80mm)
290/35 R 18	18"	11.42" (290mm)	25.99" (660.20mm)	-0.01" (-0.30mm)
295/35 R 18	18"	11.61" (295mm)	26.13" (663.70mm)	+0.13" (+3.20mm)
160/55 R 19	19"	6.30" (160mm)	25.93" (658.60mm)	-0.07" (-1.90mm)
165/55 R 19	19"	6.50" (165mm)	26.15" (664.10mm)	+0.14" (+3.60mm)
175/50 R 19	19"	6.89" (175mm)	25.89" (657.60mm)	-0.11" (-2.90mm)
180/50 R 19	19"	7.09" (180mm)	26.09" (662.60mm)	+0.08" (+2.10mm)
195/45 R 19	19"	7.68" (195mm)	25.91" (658.10mm)	-0.09" (-2.40mm)
200/45 R 19	19"	7.87" (200mm)	26.09" (662.60mm)	+0.08" (+2.10mm)
220/40 R 19	19"	8.66" (220mm)	25.93" (658.60mm)	-0.07" (-1.90mm)
225/40 R 19	19"	8.86" (225mm)	26.09" (662.60mm)	+0.08" (+2.10mm)
250/35 R 19	19"	9.84" (250mm)	25.89" (657.60mm)	-0.11" (-2.90mm)
255/35 R 19	19"	10.04" (255mm)	26.03" (661.10mm)	+0.02" (+0.60mm)
295/30 R 19	19"	11.61" (295mm)	25.97" (659.60mm)	-0.04" (-0.90mm)
300/30 R 19	19"	11.81" (300mm)	26.09" (662.60mm)	+0.08" (+2.10mm)
170/45 R 20	20"	6.69" (170mm)	26.02" (661.00mm)	+0.02" (+0.50mm)
190/40 R 20	20"	7.48" (190mm)	25.98" (660.00mm)	-0.02" (-0.50mm)
195/40 R 20	20"	7.68" (195mm)	26.14" (664.00mm)	+0.14" (+3.50mm)
215/35 R 20	20"	8.46" (215mm)	25.93" (658.50mm)	-0.08" (-2.00mm)
220/35 R 20	20"	8.66" (220mm)	26.06" (662.00mm)	+0.06" (+1.50mm)
250/30 R 20	20"	9.84" (250mm)	25.91" (658.00mm)	-0.10" (-2.50mm)
255/30 R 20	20"	10.04" (255mm)	26.02" (661.00mm)	+0.02" (+0.50mm)
260/30 R 20	20"	10.24" (260mm)	26.14" (664.00mm)	+0.14" (+3.50mm)
300/25 R 20	20"	11.81" (300mm)	25.91" (658.00mm)	-0.10" (-2.50mm)
305/25 R 20	20"	12.01" (305mm)	26.00" (660.50mm)	+0.00" (+0.00mm)
310/25 R 20	20"	12.20" (310mm)	26.10" (663.00mm)	+0.10" (+2.50mm)

Now hows that for a choice

P.S I dont think all these sizes are actually available off the shelf

[missfixit70]

I've used 225/55x17 tyres and am currently using 225/50x17. Per the satnav, the speedo very slightly under reads with the 55 profile and slightly over with the 50 profile. Therefore, technically, the 55s are illegal as your speedo should never read slower than you are actually going. However, I don't think 1mph at 70mph is too crucial Can't say I've noticed much difference in the ride quality, but my van is hardly fitted with the standard suspension

Just adjust the speedo if it is under reading, just a matter of popping the needle off

[francophile1947]

Just adjust the speedo if it is under reading, just a matter of popping the needle off

I tried that when fitting my MPH face - needle wouldn't budge, using 2 spoons as levers, so I ended up cutting the face to slide it around the needle Perhaps the speedo needles are tougher than they look, but I gave up on both of mine in case I broke them off

[missfixit70]

Or you're just a wuss

[francophile1947]

Or you're just a wuss

Sussed again

[fanx_ta_ra]

Thanks everybody for their input ....... really helpful. Now all I have to do is is find a good tyre for a good price and what with Nankangs, Linglongs and Wanlis etc etc etc I reckon I might spend a couple of hours on here later, ignoring the kids (as only a man can do ) and trawl through the archives finding out what others use and rate. Thanks again.

Andy