Tyre size question

[spikedjack]

I currently run 9.5j rears et38 with 265/35/18's

 

I need to change then pretty sharpish and want more rear grip.

 

Will 285's firstly fit on the rim? (I believe so just checking)

 

And secondly, will I need to roll the arches?

 

Thanks

 

Jack

[listy]

Personally on 9.5 I wouldn't go bigger than 275 wide.

Regarding the arches, I would say they may well need a roll. Depends how low the car is, and the offset of the wheels.

[spikedjack]

Fairly low just no tyre in the arch. Et38's

 

I fancy something with More grip so thinking if a federal 595 RS-r in 285 30 18

[listy]

I'm sure Dr Dnk will post here soon, he jumps on tyre threads lol and knows much more than me.

 

 

 

 

(Most of what I know I know from Dnk's posts and links on here )

[David P]

These might help.

 

http://www.alloywheels.com/Tyre_Calculator

 

http://www.willtheyfit.com/

 

http://www.rimsntires.com/specs.jsp

Edited March 8, 2013 by David P (see edit history)

[garethr]

http://www.carbibles.com/tyre_bible_pg4.html#ixzz2N0jndtgM

 

 

Aspect Ratio and Rim Width

Aspect ratio is the ratio of the tyre's section height to its section width. The aspect ratio is sometimes referred to as the tyre 'series'. So a 50-series tyre means one with an aspect ratio of 50%. The maths is pretty simple and the resulting figure is stamped on all tyres as part of the sizing information: aspect ratio = section height / section width

The actual dimensions of a tyre depend on the rim on which it is mounted. The biggest variable is the tyre's section width; a change of about 0.2" for every 0.5" change in rim width.

The ratio between the section width and the rim width is pretty important. If the rim width is too narrow, you pinch the tyre in and cause it to balloon more in cross-section. If the rim width is too wide, you run the risk of the tyre ripping away at high speed.

 

For 50-series tyres and above, the rim width is 70% of the tyre's section width, rounded off to the nearest 0.5.

For example, a 255/50R16 tyre has a design section width of 10.04" (255mm = 10.04 inches). 70% of 10.04" is 7.028", which, rounded to the nearest half inch, is 7". Ideally then, a 255/50R16 tyre should be mounted on a 7x16 rim.

 

For 45-series tyres and below, the rim width is 85% of the tyre's section width, rounded off to the nearest 0.5.

For example, a 255/45R17 tyre also has a design section width of 10.04" (255mm = 10.04 inches), but 85% of 10.04" is 8.534", which, rounded to the nearest half inch, is 8.5". Ideally then, a 255/45R17 tyre should be mounted on an 8½x17 rim.

 

Source: ETRTO Design manual. Yokohama Tyres

Edited March 9, 2013 by garethr (see edit history)

[Brazil]

DNK states that the maximum width tyres for a wheel that is 9.5'' wide are 265; my front wheels are 9.5'' and I've just recently ordered 265 wide tyres jumping up from 245. On the back I have 10.5'' wide and I have 295 tyres 'the maximum width' that DNK recommended.

 

I have Volk-GTC 19'' wheels with rolled arches, its very low and on 295/30/19 Toyo R888 in the rears and they only rub when I have people on the back and I go over a pump or big dip at speed.

 

I am not sure how my new front tyres are going to be if they will rub bad or not as they have not arrived yet, but they are 265/30/19 Toyo R888.

[spikedjack]

Federals own website lists a 285-30 for a 9.5j rim as a maximum which should be ok,

 

Just wondering if arches will need rolling now, the extra grip would be nice!

[Dnk]

Sizes guide for a 9.5" wheel are narrowest 245 (255 or 265 ideal width) widest 275

 

Different manufacturers will give their own fitment advice so if you can find that

out then go with that.

[dr_jekyll]

federals make fairly narrow tyres so a 285/30/18 will fit fine pm me if you want good deals on sticky tyres