Max tyre size on rim for Triumph

Just about to get some new tyres for my 14" 5.5J rims - and I want to go as wide as possible. I'm *thinking* that I might get away with 205/70/14 on these...any advice please? Ta.

Application: Triumph 2.5 PI Mk2 with Stag/2500s alloys.

Reply to
DocDelete
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I run 195/70-14 tyres on 6-inch rims - I wouldn't want to go for 205s on 5.5-inch rims myself as the sidewalls will be bowed-in a bit too much for my tastes.

Reply to
PJML

Also beware that in changing the tyre width you will change the rolling radius & so the gearing if you don't adjust the profile to compensate. What's on the car now?

I
Reply to
Iain Miller

Physically possible (check wheel arch clearance) but definitely not adviseable this is the extreme to end of what will fit on the rim, for best handling the tyre size should be at the narrower end of sizes suitable for the rim width. 185/70x14 would be a better choice or at a pinch 195/65x14.

Reply to
awm

Changing the width doesn't change the radius. Changing the diameter ie from

13" to 14" does. I think this is what you mean.

Steve

Reply to
shazzbat

Erm, yes it does :)

There are three given measurements to a tyre, the inner diameter, the width, and the profile. The profile is a percentage measurement of the width, ergo any change to the width of a tyre (whilst retaining the same profile) will result in a change in the rolling radius (e.g. the 70 in

205/70 R14 means 70 percent of 205mm, if he changed to those from 155/70 R14 tyres then it would have been 70 percent of 155mm.

No, it's not. The difference however is marginal and not worth worrying about, and seeing as speedos over-read anyway it may even make it *more* accurate than it was previously (obviously depends on the exact changes taking place in the rolling radius).

Reply to
Lordy

All right, all right, *effectively* doesn't, because it's such a miniscule amount.

Changing the diameter affects gearing/speedo reading, Changing profile affects it less, changing width affects it not enough to be noticeable.

*for practical purposes*

happy now?

Reply to
shazzbat

Stick with the recommended tyre size for the prescribe rims. Triumph should show a tyre size.

The Doggimite Sprint shows a 175/? x13 and I went to 185/? x13 this was quite sufficient increase as the smaller size became unpopular and harder to obtain a decent tyre. ( not sure what profile it was but still kept the rolling radius).

I would think that 205/70/14 may cause problems and may not go under the guards.

r
Reply to
ops

Thanks - any reason you didn't suggest 195/**70** x 14? I've seen this option available on all the internet traders I've looked at.

-- Ken Davidson

Reply to
DocDelete

Hehe, quick thinking :)

Reply to
Lordy

The "standard" profile is 82 IIRC so your original tyres are 185 x 13 x 82. If I read what you are saying correctly they also fitted 185x14x82 - that'd be quite a big jump in gearing - are you sure they didn't change the diff ratio when they did that? If you were staying on 13s I'd say your options would be something like 195x70s or 205x65 or 205x60 if you could get them on the rims. Going up to 14s I'd say you'd need a much lower profile tyre to compensate - maybe a 185x60 or a 195x55

I.

Reply to
Iain Miller

Don't confuse section size and tyre width

Reply to
awm

It would just bee too big a 195/65x14 is more likely to clear the wheel arches and because of the slightly lower profile is less likely to affect the handling. 175/65x14 is also worth considering as its cheap and easily available and would give better handling.

When the tyre is wider than the rim the tyre wall is cantilevered outwards and as result tends to roll about and gives poor imprecise handling. This is why Lotus cars tend to come from the factory with wide rims but tyres that are quite narrow, the Elan when fitted with 5.5jx13 rims used 165x13 or even 155x13 tyres. With tyres it is always better to invest in a quality tyre rather than squeezing extra width on an existing rim.

Reply to
awm

Reply to
leithant

My car comes with 225 width on an 8J rim. I think you're trying to go much too far!

Reply to
TimM

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